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ClamAV is an open source (GPLv2) anti-virus toolkit.
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clamav/libclamav/pe.c

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/*
* Copyright (C) 2004 - 2006 Tomasz Kojm <tkojm@clamav.net>
* aCaB <acab@clamav.net>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*/
#if HAVE_CONFIG_H
#include "clamav-config.h"
#endif
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/stat.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <time.h>
#include "cltypes.h"
#include "clamav.h"
#include "others.h"
#include "pe.h"
#include "petite.h"
#include "fsg.h"
#include "spin.h"
#include "upx.h"
#include "yc.h"
#include "wwunpack.h"
#include "suecrypt.h"
#include "unsp.h"
#include "scanners.h"
#include "str.h"
#include "execs.h"
#include "md5.h"
#include "mew.h"
#include "upack.h"
#ifndef O_BINARY
#define O_BINARY 0
#endif
#define DCONF ctx->dconf->pe
#define IMAGE_DOS_SIGNATURE 0x5a4d /* MZ */
#define IMAGE_DOS_SIGNATURE_OLD 0x4d5a /* ZM */
#define IMAGE_NT_SIGNATURE 0x00004550
#define PE32_SIGNATURE 0x010b
#define PE32P_SIGNATURE 0x020b
#define optional_hdr64 pe_opt.opt64
#define optional_hdr32 pe_opt.opt32
#define UPX_NRV2B "\x11\xdb\x11\xc9\x01\xdb\x75\x07\x8b\x1e\x83\xee\xfc\x11\xdb\x11\xc9\x11\xc9\x75\x20\x41\x01\xdb"
#define UPX_NRV2D "\x83\xf0\xff\x74\x78\xd1\xf8\x89\xc5\xeb\x0b\x01\xdb\x75\x07\x8b\x1e\x83\xee\xfc\x11\xdb\x11\xc9"
#define UPX_NRV2E "\xeb\x52\x31\xc9\x83\xe8\x03\x72\x11\xc1\xe0\x08\x8a\x06\x46\x83\xf0\xff\x74\x75\xd1\xf8\x89\xc5"
#define EC32(x) le32_to_host(x) /* Convert little endian to host */
#define EC16(x) le16_to_host(x)
/* lower and upper bondary alignment (size vs offset) */
#define PEALIGN(o,a) (((a))?(((o)/(a))*(a)):(o))
#define PESALIGN(o,a) (((a))?(((o)/(a)+((o)%(a)!=0))*(a)):(o))
extern short cli_leavetemps_flag;
struct offset_list {
uint32_t offset;
struct offset_list *next;
};
static uint32_t cli_rawaddr(uint32_t rva, struct cli_exe_section *shp, uint16_t nos, unsigned int *err, size_t fsize, uint32_t hdr_size)
{
int i, found = 0;
uint32_t ret;
if (rva<hdr_size) { /* Out of section EP - mapped to imagebase+rva */
if (rva >= fsize) {
*err=1;
return 0;
}
*err=0;
return rva;
}
for(i = nos-1; i >= 0; i--) {
if(shp[i].rsz && shp[i].rva <= rva && shp[i].rsz > rva - shp[i].rva) {
found = 1;
break;
}
}
if(!found) {
*err = 1;
return 0;
}
ret = rva - shp[i].rva + shp[i].raw;
*err = 0;
return ret;
}
static void xckriz(char **opcode, int *len, int checksize, int reg) {
while(*len>6) {
if (**opcode>='\x48' && **opcode<='\x4f' && **opcode!='\x4c') {
if ((char)(**opcode-reg)=='\x48') break;
(*len)--;
(*opcode)++;
continue;
}
if (**opcode>='\xb8' && **opcode<='\xbf' && **opcode!='\xbc') {
if (checksize && cli_readint32(*opcode+1)==0x0fd2) break;
(*len)-=5;
(*opcode)+=5;
continue;
}
if (**opcode=='\x81') {
(*len)-=6;
(*opcode)+=6;
continue;
}
break;
}
}
/*
static int cli_ddump(int desc, int offset, int size, const char *file)
{
int pos, ndesc, bread, sum = 0;
char buff[FILEBUFF];
cli_dbgmsg("in ddump()\n");
if((pos = lseek(desc, 0, SEEK_CUR)) == -1) {
cli_dbgmsg("Invalid descriptor\n");
return -1;
}
if(lseek(desc, offset, SEEK_SET) == -1) {
cli_dbgmsg("lseek() failed\n");
lseek(desc, pos, SEEK_SET);
return -1;
}
if((ndesc = open(file, O_WRONLY|O_CREAT|O_TRUNC|O_BINARY, S_IRWXU)) < 0) {
cli_dbgmsg("Can't create file %s\n", file);
lseek(desc, pos, SEEK_SET);
return -1;
}
while((bread = cli_readn(desc, buff, FILEBUFF)) > 0) {
if(sum + bread >= size) {
if(write(ndesc, buff, size - sum) == -1) {
cli_dbgmsg("Can't write to file\n");
lseek(desc, pos, SEEK_SET);
close(ndesc);
unlink(file);
return -1;
}
break;
} else {
if(write(ndesc, buff, bread) == -1) {
cli_dbgmsg("Can't write to file\n");
lseek(desc, pos, SEEK_SET);
close(ndesc);
unlink(file);
return -1;
}
}
sum += bread;
}
close(ndesc);
lseek(desc, pos, SEEK_SET);
return 0;
}
*/
static unsigned int cli_md5sect(int fd, uint32_t offset, uint32_t size, unsigned char *digest)
{
size_t bread, sum = 0;
off_t pos;
char buff[FILEBUFF];
cli_md5_ctx md5ctx;
if((pos = lseek(fd, 0, SEEK_CUR)) == -1) {
cli_dbgmsg("cli_md5sect: Invalid descriptor %d\n", fd);
return 0;
}
if(lseek(fd, offset, SEEK_SET) == -1) {
cli_dbgmsg("cli_md5sect: lseek() failed\n");
lseek(fd, pos, SEEK_SET);
return 0;
}
cli_md5_init(&md5ctx);
while((bread = cli_readn(fd, buff, FILEBUFF)) > 0) {
if(sum + bread >= size) {
cli_md5_update(&md5ctx, buff, size - sum);
break;
} else {
cli_md5_update(&md5ctx, buff, bread);
sum += bread;
}
}
cli_md5_final(digest, &md5ctx);
lseek(fd, pos, SEEK_SET);
return 1;
}
int cli_scanpe(int desc, cli_ctx *ctx)
{
uint16_t e_magic; /* DOS signature ("MZ") */
uint16_t nsections;
uint32_t e_lfanew; /* address of new exe header */
uint32_t ep, vep; /* entry point (raw, virtual) */
uint8_t polipos = 0;
time_t timestamp;
struct pe_image_file_hdr file_hdr;
union {
struct pe_image_optional_hdr64 opt64;
struct pe_image_optional_hdr32 opt32;
} pe_opt;
struct pe_image_section_hdr *section_hdr;
struct cli_md5_node *md5_sect;
struct stat sb;
char sname[9], buff[4096], *tempfile;
unsigned char *ubuff;
ssize_t bytes;
unsigned int i, found, upx_success = 0, min = 0, max = 0, err;
unsigned int ssize = 0, dsize = 0, dll = 0, pe_plus = 0;
int (*upxfn)(char *, uint32_t, char *, uint32_t *, uint32_t, uint32_t, uint32_t) = NULL;
char *src = NULL, *dest = NULL;
int ndesc, ret = CL_CLEAN, upack = 0, native=0;
size_t fsize;
uint32_t valign, falign, hdr_size;
struct cli_exe_section *exe_sections;
if(cli_readn(desc, &e_magic, sizeof(e_magic)) != sizeof(e_magic)) {
cli_dbgmsg("Can't read DOS signature\n");
return CL_CLEAN;
}
if(EC16(e_magic) != IMAGE_DOS_SIGNATURE && EC16(e_magic) != IMAGE_DOS_SIGNATURE_OLD) {
cli_dbgmsg("Invalid DOS signature\n");
return CL_CLEAN;
}
lseek(desc, 58, SEEK_CUR); /* skip to the end of the DOS header */
if(cli_readn(desc, &e_lfanew, sizeof(e_lfanew)) != sizeof(e_lfanew)) {
cli_dbgmsg("Can't read new header address\n");
/* truncated header? */
if(DETECT_BROKEN) {
if(ctx->virname)
*ctx->virname = "Broken.Executable";
return CL_VIRUS;
}
return CL_CLEAN;
}
e_lfanew = EC32(e_lfanew);
cli_dbgmsg("e_lfanew == %d\n", e_lfanew);
if(!e_lfanew) {
cli_dbgmsg("Not a PE file\n");
return CL_CLEAN;
}
if(lseek(desc, e_lfanew, SEEK_SET) < 0) {
/* probably not a PE file */
cli_dbgmsg("Can't lseek to e_lfanew\n");
return CL_CLEAN;
}
if(cli_readn(desc, &file_hdr, sizeof(struct pe_image_file_hdr)) != sizeof(struct pe_image_file_hdr)) {
/* bad information in e_lfanew - probably not a PE file */
cli_dbgmsg("Can't read file header\n");
return CL_CLEAN;
}
if(EC32(file_hdr.Magic) != IMAGE_NT_SIGNATURE) {
cli_dbgmsg("Invalid PE signature (probably NE file)\n");
return CL_CLEAN;
}
if(EC16(file_hdr.Characteristics) & 0x2000) {
cli_dbgmsg("File type: DLL\n");
dll = 1;
} else if(EC16(file_hdr.Characteristics) & 0x01) {
cli_dbgmsg("File type: Executable\n");
}
switch(EC16(file_hdr.Machine)) {
case 0x0:
cli_dbgmsg("Machine type: Unknown\n");
case 0x14c:
cli_dbgmsg("Machine type: 80386\n");
break;
case 0x14d:
cli_dbgmsg("Machine type: 80486\n");
break;
case 0x14e:
cli_dbgmsg("Machine type: 80586\n");
break;
case 0x160:
cli_dbgmsg("Machine type: R30000 (big-endian)\n");
break;
case 0x162:
cli_dbgmsg("Machine type: R3000\n");
break;
case 0x166:
cli_dbgmsg("Machine type: R4000\n");
break;
case 0x168:
cli_dbgmsg("Machine type: R10000\n");
break;
case 0x184:
cli_dbgmsg("Machine type: DEC Alpha AXP\n");
break;
case 0x284:
cli_dbgmsg("Machine type: DEC Alpha AXP 64bit\n");
break;
case 0x1f0:
cli_dbgmsg("Machine type: PowerPC\n");
break;
case 0x200:
cli_dbgmsg("Machine type: IA64\n");
break;
case 0x268:
cli_dbgmsg("Machine type: M68k\n");
break;
case 0x266:
cli_dbgmsg("Machine type: MIPS16\n");
break;
case 0x366:
cli_dbgmsg("Machine type: MIPS+FPU\n");
break;
case 0x466:
cli_dbgmsg("Machine type: MIPS16+FPU\n");
break;
case 0x1a2:
cli_dbgmsg("Machine type: Hitachi SH3\n");
break;
case 0x1a3:
cli_dbgmsg("Machine type: Hitachi SH3-DSP\n");
break;
case 0x1a4:
cli_dbgmsg("Machine type: Hitachi SH3-E\n");
break;
case 0x1a6:
cli_dbgmsg("Machine type: Hitachi SH4\n");
break;
case 0x1a8:
cli_dbgmsg("Machine type: Hitachi SH5\n");
break;
case 0x1c0:
cli_dbgmsg("Machine type: ARM\n");
break;
case 0x1c2:
cli_dbgmsg("Machine type: THUMB\n");
break;
case 0x1d3:
cli_dbgmsg("Machine type: AM33\n");
break;
case 0x520:
cli_dbgmsg("Machine type: Infineon TriCore\n");
break;
case 0xcef:
cli_dbgmsg("Machine type: CEF\n");
break;
case 0xebc:
cli_dbgmsg("Machine type: EFI Byte Code\n");
break;
case 0x9041:
cli_dbgmsg("Machine type: M32R\n");
break;
case 0xc0ee:
cli_dbgmsg("Machine type: CEE\n");
break;
case 0x8664:
cli_dbgmsg("Machine type: AMD64\n");
break;
default:
cli_warnmsg("Unknown machine type in PE header (0x%x)\n", EC16(file_hdr.Machine));
}
nsections = EC16(file_hdr.NumberOfSections);
if(nsections < 1 || nsections > 96) {
if(DETECT_BROKEN) {
if(ctx->virname)
*ctx->virname = "Broken.Executable";
return CL_VIRUS;
}
if(nsections)
cli_warnmsg("PE file contains %d sections\n", nsections);
else
cli_warnmsg("PE file contains no sections\n");
return CL_CLEAN;
}
cli_dbgmsg("NumberOfSections: %d\n", nsections);
timestamp = (time_t) EC32(file_hdr.TimeDateStamp);
cli_dbgmsg("TimeDateStamp: %s", ctime(&timestamp));
cli_dbgmsg("SizeOfOptionalHeader: %x\n", EC16(file_hdr.SizeOfOptionalHeader));
if (EC16(file_hdr.SizeOfOptionalHeader) < sizeof(struct pe_image_optional_hdr32)) {
cli_dbgmsg("SizeOfOptionalHeader too small\n");
if(DETECT_BROKEN) {
if(ctx->virname)
*ctx->virname = "Broken.Executable";
return CL_VIRUS;
}
return CL_CLEAN;
}
if(cli_readn(desc, &optional_hdr32, sizeof(struct pe_image_optional_hdr32)) != sizeof(struct pe_image_optional_hdr32)) {
cli_dbgmsg("Can't read optional file header\n");
if(DETECT_BROKEN) {
if(ctx->virname)
*ctx->virname = "Broken.Executable";
return CL_VIRUS;
}
return CL_CLEAN;
}
/* This will be a chicken and egg problem until we drop 9x */
if(EC32(optional_hdr64.Magic)==PE32P_SIGNATURE) {
if(EC16(file_hdr.SizeOfOptionalHeader)!=sizeof(struct pe_image_optional_hdr64)) {
/* FIXME: need to play around a bit more with xp64 */
cli_dbgmsg("Incorrect SizeOfOptionalHeader for PE32+\n");
if(DETECT_BROKEN) {
if(ctx->virname)
*ctx->virname = "Broken.Executable";
return CL_VIRUS;
}
return CL_CLEAN;
}
pe_plus = 1;
} else {
/*
either it's got a PE32_SIGNATURE or
we enable win9x compatibility in that we don't honor magic (see bb#119)
either way it's a 32bit thingy
*/
if(EC16(optional_hdr32.Magic) != PE32_SIGNATURE) {
cli_warnmsg("Incorrect magic number in optional header\n");
if(DETECT_BROKEN) {
if(ctx->virname)
*ctx->virname = "Broken.Executable";
return CL_VIRUS;
}
cli_dbgmsg("9x compatibility mode\n");
}
}
if(!pe_plus) { /* PE */
if (EC16(file_hdr.SizeOfOptionalHeader)!=sizeof(struct pe_image_optional_hdr32)) {
/* Seek to the end of the long header */
lseek(desc, (EC16(file_hdr.SizeOfOptionalHeader)-sizeof(struct pe_image_optional_hdr32)), SEEK_CUR);
}
if(DCONF & PE_CONF_UPACK)
upack = (EC16(file_hdr.SizeOfOptionalHeader)==0x148);
vep = EC32(optional_hdr32.AddressOfEntryPoint);
hdr_size = EC32(optional_hdr32.SizeOfHeaders);
cli_dbgmsg("File format: PE\n");
cli_dbgmsg("MajorLinkerVersion: %d\n", optional_hdr32.MajorLinkerVersion);
cli_dbgmsg("MinorLinkerVersion: %d\n", optional_hdr32.MinorLinkerVersion);
cli_dbgmsg("SizeOfCode: 0x%x\n", EC32(optional_hdr32.SizeOfCode));
cli_dbgmsg("SizeOfInitializedData: 0x%x\n", EC32(optional_hdr32.SizeOfInitializedData));
cli_dbgmsg("SizeOfUninitializedData: 0x%x\n", EC32(optional_hdr32.SizeOfUninitializedData));
cli_dbgmsg("AddressOfEntryPoint: 0x%x\n", vep);
cli_dbgmsg("BaseOfCode: 0x%x\n", EC32(optional_hdr32.BaseOfCode));
cli_dbgmsg("SectionAlignment: 0x%x\n", EC32(optional_hdr32.SectionAlignment));
cli_dbgmsg("FileAlignment: 0x%x\n", EC32(optional_hdr32.FileAlignment));
cli_dbgmsg("MajorSubsystemVersion: %d\n", EC16(optional_hdr32.MajorSubsystemVersion));
cli_dbgmsg("MinorSubsystemVersion: %d\n", EC16(optional_hdr32.MinorSubsystemVersion));
cli_dbgmsg("SizeOfImage: 0x%x\n", EC32(optional_hdr32.SizeOfImage));
cli_dbgmsg("SizeOfHeaders: 0x%x\n", hdr_size);
cli_dbgmsg("NumberOfRvaAndSizes: %d\n", EC32(optional_hdr32.NumberOfRvaAndSizes));
} else { /* PE+ */
/* read the remaining part of the header */
if(cli_readn(desc, &optional_hdr32 + 1, sizeof(struct pe_image_optional_hdr64) - sizeof(struct pe_image_optional_hdr32)) != sizeof(struct pe_image_optional_hdr64) - sizeof(struct pe_image_optional_hdr32)) {
cli_dbgmsg("Can't read optional file header\n");
if(DETECT_BROKEN) {
if(ctx->virname)
*ctx->virname = "Broken.Executable";
return CL_VIRUS;
}
return CL_CLEAN;
}
vep = EC32(optional_hdr64.AddressOfEntryPoint);
hdr_size = EC32(optional_hdr64.SizeOfHeaders);
cli_dbgmsg("File format: PE32+\n");
cli_dbgmsg("MajorLinkerVersion: %d\n", optional_hdr64.MajorLinkerVersion);
cli_dbgmsg("MinorLinkerVersion: %d\n", optional_hdr64.MinorLinkerVersion);
cli_dbgmsg("SizeOfCode: 0x%x\n", EC32(optional_hdr64.SizeOfCode));
cli_dbgmsg("SizeOfInitializedData: 0x%x\n", EC32(optional_hdr64.SizeOfInitializedData));
cli_dbgmsg("SizeOfUninitializedData: 0x%x\n", EC32(optional_hdr64.SizeOfUninitializedData));
cli_dbgmsg("AddressOfEntryPoint: 0x%x\n", vep);
cli_dbgmsg("BaseOfCode: 0x%x\n", EC32(optional_hdr64.BaseOfCode));
cli_dbgmsg("SectionAlignment: 0x%x\n", EC32(optional_hdr64.SectionAlignment));
cli_dbgmsg("FileAlignment: 0x%x\n", EC32(optional_hdr64.FileAlignment));
cli_dbgmsg("MajorSubsystemVersion: %d\n", EC16(optional_hdr64.MajorSubsystemVersion));
cli_dbgmsg("MinorSubsystemVersion: %d\n", EC16(optional_hdr64.MinorSubsystemVersion));
cli_dbgmsg("SizeOfImage: 0x%x\n", EC32(optional_hdr64.SizeOfImage));
cli_dbgmsg("SizeOfHeaders: 0x%x\n", hdr_size);
cli_dbgmsg("NumberOfRvaAndSizes: %d\n", EC32(optional_hdr64.NumberOfRvaAndSizes));
}
switch(pe_plus ? EC16(optional_hdr64.Subsystem) : EC16(optional_hdr32.Subsystem)) {
case 0:
cli_dbgmsg("Subsystem: Unknown\n");
break;
case 1:
cli_dbgmsg("Subsystem: Native (svc)\n");
native = 1;
break;
case 2:
cli_dbgmsg("Subsystem: Win32 GUI\n");
break;
case 3:
cli_dbgmsg("Subsystem: Win32 console\n");
break;
case 5:
cli_dbgmsg("Subsystem: OS/2 console\n");
break;
case 7:
cli_dbgmsg("Subsystem: POSIX console\n");
break;
case 8:
cli_dbgmsg("Subsystem: Native Win9x driver\n");
break;
case 9:
cli_dbgmsg("Subsystem: WinCE GUI\n");
break;
case 10:
cli_dbgmsg("Subsystem: EFI application\n");
break;
case 11:
cli_dbgmsg("Subsystem: EFI driver\n");
break;
case 12:
cli_dbgmsg("Subsystem: EFI runtime driver\n");
break;
default:
cli_warnmsg("Unknown subsystem in PE header (0x%x)\n", pe_plus ? EC16(optional_hdr64.Subsystem) : EC16(optional_hdr32.Subsystem));
}
cli_dbgmsg("------------------------------------\n");
if (DETECT_BROKEN && !native && (!(pe_plus?EC32(optional_hdr64.SectionAlignment):EC32(optional_hdr32.SectionAlignment)) || (pe_plus?EC32(optional_hdr64.SectionAlignment):EC32(optional_hdr32.SectionAlignment))%0x1000)) {
cli_dbgmsg("Bad virtual alignemnt\n");
if(ctx->virname)
*ctx->virname = "Broken.Executable";
return CL_VIRUS;
}
if (DETECT_BROKEN && !native && (!(pe_plus?EC32(optional_hdr64.FileAlignment):EC32(optional_hdr32.FileAlignment)) || (pe_plus?EC32(optional_hdr64.FileAlignment):EC32(optional_hdr32.FileAlignment))%0x200)) {
cli_dbgmsg("Bad file alignemnt\n");
if(ctx->virname)
*ctx->virname = "Broken.Executable";
return CL_VIRUS;
}
if(fstat(desc, &sb) == -1) {
cli_dbgmsg("fstat failed\n");
return CL_EIO;
}
fsize = sb.st_size;
section_hdr = (struct pe_image_section_hdr *) cli_calloc(nsections, sizeof(struct pe_image_section_hdr));
if(!section_hdr) {
cli_dbgmsg("Can't allocate memory for section headers\n");
return CL_EMEM;
}
exe_sections = (struct cli_exe_section *) cli_calloc(nsections, sizeof(struct cli_exe_section));
if(!exe_sections) {
cli_dbgmsg("Can't allocate memory for section headers\n");
free(section_hdr);
return CL_EMEM;
}
valign = (pe_plus)?EC32(optional_hdr64.SectionAlignment):EC32(optional_hdr32.SectionAlignment);
falign = (pe_plus)?EC32(optional_hdr64.FileAlignment):EC32(optional_hdr32.FileAlignment);
if(cli_readn(desc, section_hdr, sizeof(struct pe_image_section_hdr)*nsections) != (int)(nsections*sizeof(struct pe_image_section_hdr))) {
cli_dbgmsg("Can't read section header\n");
cli_dbgmsg("Possibly broken PE file\n");
free(section_hdr);
free(exe_sections);
if(DETECT_BROKEN) {
if(ctx->virname)
*ctx->virname = "Broken.Executable";
return CL_VIRUS;
}
return CL_CLEAN;
}
for(i = 0; falign!=0x200 && i<nsections; i++) {
/* file alignment fallback mode - blah */
if (falign && section_hdr[i].SizeOfRawData && EC32(section_hdr[i].PointerToRawData)%falign && !(EC32(section_hdr[i].PointerToRawData)%0x200)) {
cli_dbgmsg("Found misaligned section, using 0x200\n");
falign = 0x200;
}
}
hdr_size = PESALIGN(hdr_size, valign); /* Aligned headers virtual size */
for(i = 0; i < nsections; i++) {
strncpy(sname, (char *) section_hdr[i].Name, 8);
sname[8] = 0;
exe_sections[i].rva = PEALIGN(EC32(section_hdr[i].VirtualAddress), valign);
exe_sections[i].vsz = PESALIGN(EC32(section_hdr[i].VirtualSize), valign);
exe_sections[i].raw = PEALIGN(EC32(section_hdr[i].PointerToRawData), falign);
exe_sections[i].rsz = PESALIGN(EC32(section_hdr[i].SizeOfRawData), falign);
exe_sections[i].chr = EC32(section_hdr[i].Characteristics);
exe_sections[i].urva = EC32(section_hdr[i].VirtualAddress); /* Just in case */
exe_sections[i].uvsz = EC32(section_hdr[i].VirtualSize);
exe_sections[i].uraw = EC32(section_hdr[i].PointerToRawData);
exe_sections[i].ursz = EC32(section_hdr[i].SizeOfRawData);
if (!exe_sections[i].vsz && exe_sections[i].rsz)
exe_sections[i].vsz=PESALIGN(exe_sections[i].ursz, valign);
if (exe_sections[i].rsz && fsize>exe_sections[i].raw && !CLI_ISCONTAINED(0, (uint32_t) fsize, exe_sections[i].raw, exe_sections[i].rsz))
exe_sections[i].rsz = fsize - exe_sections[i].raw;
cli_dbgmsg("Section %d\n", i);
cli_dbgmsg("Section name: %s\n", sname);
cli_dbgmsg("Section data (from headers - in memory)\n");
cli_dbgmsg("VirtualSize: 0x%x 0x%x\n", exe_sections[i].uvsz, exe_sections[i].vsz);
cli_dbgmsg("VirtualAddress: 0x%x 0x%x\n", exe_sections[i].urva, exe_sections[i].rva);
cli_dbgmsg("SizeOfRawData: 0x%x 0x%x\n", exe_sections[i].ursz, exe_sections[i].rsz);
cli_dbgmsg("PointerToRawData: 0x%x 0x%x\n", exe_sections[i].uraw, exe_sections[i].raw);
if(exe_sections[i].chr & 0x20) {
cli_dbgmsg("Section contains executable code\n");
if(exe_sections[i].vsz < exe_sections[i].rsz) {
cli_dbgmsg("Section contains free space\n");
/*
cli_dbgmsg("Dumping %d bytes\n", section_hdr.SizeOfRawData - section_hdr.VirtualSize);
ddump(desc, section_hdr.PointerToRawData + section_hdr.VirtualSize, section_hdr.SizeOfRawData - section_hdr.VirtualSize, cli_gentemp(NULL));
*/
}
}
if(exe_sections[i].chr & 0x20000000)
cli_dbgmsg("Section's memory is executable\n");
if(exe_sections[i].chr & 0x80000000)
cli_dbgmsg("Section's memory is writeable\n");
cli_dbgmsg("------------------------------------\n");
if (DETECT_BROKEN && (exe_sections[i].urva % valign)) { /* Bad virtual alignment */
cli_dbgmsg("VirtualAddress is misaligned\n");
if(ctx->virname)
*ctx->virname = "Broken.Executable";
free(section_hdr);
free(exe_sections);
return CL_VIRUS;
}
if (exe_sections[i].rsz) { /* Don't bother with virtual only sections */
unsigned char md5_dig[16];
if (exe_sections[i].raw >= fsize) { /* really broken */
cli_dbgmsg("Broken PE file - Section %d starts beyond the end of file (Offset@ %d, Total filesize %d)\n", i, exe_sections[i].raw, fsize);
free(section_hdr);
free(exe_sections);
if(DETECT_BROKEN) {
if(ctx->virname)
*ctx->virname = "Broken.Executable";
return CL_VIRUS;
}
return CL_CLEAN; /* no ninjas to see here! move along! */
}
/* check MD5 section sigs */
if(DCONF & PE_CONF_MD5SECT)
md5_sect = ctx->engine->md5_sect;
else
md5_sect = NULL;
while(md5_sect && md5_sect->size < exe_sections[i].rsz)
md5_sect = md5_sect->next;
if(md5_sect && md5_sect->size == exe_sections[i].rsz) {
if(!cli_md5sect(desc, exe_sections[i].raw, exe_sections[i].rsz, md5_dig)) {
cli_errmsg("PE: Can't calculate MD5 for section %d\n", i);
} else {
while(md5_sect && md5_sect->size == exe_sections[i].rsz) {
if(!memcmp(md5_dig, md5_sect->md5, 16)) {
if(ctx->virname)
*ctx->virname = md5_sect->virname;
free(section_hdr);
free(exe_sections);
return CL_VIRUS;
}
md5_sect = md5_sect->next;
}
}
}
}
if(!i) {
if (DETECT_BROKEN && exe_sections[i].urva!=hdr_size) { /* Bad first section RVA */
cli_dbgmsg("First section is in the wrong place\n");
if(ctx->virname)
*ctx->virname = "Broken.Executable";
free(section_hdr);
free(exe_sections);
return CL_VIRUS;
}
min = exe_sections[i].rva;
max = exe_sections[i].rva + exe_sections[i].rsz;
} else {
if (DETECT_BROKEN && exe_sections[i].urva - exe_sections[i-1].urva != exe_sections[i-1].vsz) { /* No holes, no overlapping, no virtual disorder */
cli_dbgmsg("Virtually misplaced section (wrong order, overlapping, non contiguous)\n");
if(ctx->virname)
*ctx->virname = "Broken.Executable";
free(section_hdr);
free(exe_sections);
return CL_VIRUS;
}
if(exe_sections[i].rva < min)
min = exe_sections[i].rva;
if(exe_sections[i].rva + exe_sections[i].rsz > max)
max = exe_sections[i].rva + exe_sections[i].rsz;
}
if(SCAN_ALGO && (DCONF & PE_CONF_POLIPOS) && !strlen(sname)) {
if(exe_sections[i].vsz > 40000 && exe_sections[i].vsz < 70000) {
if(exe_sections[i].chr == 0xe0000060) {
polipos = i;
}
}
}
}
free(section_hdr);
if(!(ep = cli_rawaddr(vep, exe_sections, nsections, &err, fsize, hdr_size)) && err) {
cli_dbgmsg("EntryPoint out of file\n");
free(exe_sections);
if(DETECT_BROKEN) {
if(ctx->virname)
*ctx->virname = "Broken.Executable";
return CL_VIRUS;
}
return CL_CLEAN;
}
cli_dbgmsg("EntryPoint offset: 0x%x (%d)\n", ep, ep);
if(pe_plus) { /* Do not continue for PE32+ files */
free(exe_sections);
return CL_CLEAN;
}
/* Attempt to detect some popular polymorphic viruses */
/* W32.Parite.B */
if(SCAN_ALGO && (DCONF & PE_CONF_PARITE) && !dll && ep == exe_sections[nsections - 1].raw) {
lseek(desc, ep, SEEK_SET);
if(cli_readn(desc, buff, 4096) == 4096) {
const char *pt = cli_memstr(buff, 4040, "\x47\x65\x74\x50\x72\x6f\x63\x41\x64\x64\x72\x65\x73\x73\x00", 15);
if(pt) {
uint32_t dw1, dw2;
pt += 15;
if(((dw1 = cli_readint32(pt)) ^ (dw2 = cli_readint32(pt + 4))) == 0x505a4f && ((dw1 = cli_readint32(pt + 8)) ^ (dw2 = cli_readint32(pt + 12))) == 0xffffb && ((dw1 = cli_readint32(pt + 16)) ^ (dw2 = cli_readint32(pt + 20))) == 0xb8) {
*ctx->virname = "W32.Parite.B";
free(exe_sections);
return CL_VIRUS;
}
}
}
}
/* Kriz */
if(SCAN_ALGO && (DCONF & PE_CONF_KRIZ) && CLI_ISCONTAINED(exe_sections[nsections - 1].raw, exe_sections[nsections - 1].rsz, ep, 0x0fd2)) {
cli_dbgmsg("in kriz\n");
lseek(desc, ep, SEEK_SET);
if(cli_readn(desc, buff, 200) == 200) {
while (1) {
char *krizpos=buff+3;
char *krizmov, *krizxor;
int krizleft = 200-3;
int krizrega,krizregb;
if (buff[1]!='\x9c' || buff[2]!='\x60') break; /* EP+1 */
xckriz(&krizpos, &krizleft, 0, 8);
if (krizleft < 6 || *krizpos!='\xe8' || krizpos[2] || krizpos[3] || krizpos[4]) break; /* call DELTA */
krizleft-=5+(unsigned char)krizpos[1];
if (krizleft < 2) break;
krizpos+=5+(unsigned char)krizpos[1];
if (*krizpos<'\x58' || *krizpos>'\x5f' || *krizpos=='\x5c') break; /* pop DELTA */
krizrega=*krizpos-'\x58';
cli_dbgmsg("kriz: pop delta using %d\n", krizrega);
krizpos+=1;
krizleft-=1;
xckriz(&krizpos, &krizleft, 1, 8);
if (krizleft <6 || *krizpos<'\xb8' || *krizpos>'\xbf' || *krizpos=='\xbc' || cli_readint32(krizpos+1)!=0x0fd2) break;
krizregb=*krizpos-'\xb8';
if (krizrega==krizregb) break;
cli_dbgmsg("kriz: using %d for size\n", krizregb);
krizpos+=5;
krizleft-=5;
krizmov = krizpos;
xckriz(&krizpos, &krizleft, 0, 8);
krizxor=krizpos;
if (krizleft && *krizpos=='\x3e') {
/* strip ds: */
krizpos++;
krizleft--;
}
if (krizleft<8 || *krizpos!='\x80' || (char)(krizpos[1]-krizrega)!='\xb0') {
cli_dbgmsg("kriz: bogus opcode or register\n");
break;
}
krizpos+=7;
krizleft-=7;
xckriz(&krizpos, &krizleft, 0, krizrega);
if (! krizleft || (char)(*krizpos-krizrega)!='\x48') break; /* dec delta */
krizpos++;
krizleft--;
cli_dbgmsg("kriz: dec delta found\n");
xckriz(&krizpos, &krizleft, 0, krizregb);
if (krizleft <4 || (char)(*krizpos-krizregb)!='\x48' || krizpos[1]!='\x75') break; /* dec size + jne loop */
if (krizpos+3+(int)krizpos[2]<krizmov || krizpos+3+(int)krizpos[2]>krizxor) {
cli_dbgmsg("kriz: jmp back out of range (%d>%d>%d)\n", krizmov-(krizpos+3), (int)krizpos[2], krizxor-(krizpos+3));
break;
}
*ctx->virname = "Win32.Kriz";
free(exe_sections);
return CL_VIRUS;
}
}
}
/* W32.Magistr.A/B */
if(SCAN_ALGO && (DCONF & PE_CONF_MAGISTR) && !dll && (nsections>1) && (exe_sections[nsections - 1].chr & 0x80000000)) {
uint32_t rsize, vsize, dam = 0;
vsize = exe_sections[nsections - 1].uvsz;
rsize = exe_sections[nsections - 1].rsz;
if(rsize < exe_sections[nsections - 1].ursz) {
rsize = exe_sections[nsections - 1].ursz;
dam = 1;
}
if(vsize >= 0x612c && rsize >= 0x612c && ((vsize & 0xff) == 0xec)) {
int bw = rsize < 0x7000 ? rsize : 0x7000;
lseek(desc, exe_sections[nsections - 1].raw + rsize - bw, SEEK_SET);
if(cli_readn(desc, buff, 4096) == 4096) {
if(cli_memstr(buff, 4091, "\xe8\x2c\x61\x00\x00", 5)) {
*ctx->virname = dam ? "W32.Magistr.A.dam" : "W32.Magistr.A";
free(exe_sections);
return CL_VIRUS;
}
}
} else if(rsize >= 0x7000 && vsize >= 0x7000 && ((vsize & 0xff) == 0xed)) {
int bw = rsize < 0x8000 ? rsize : 0x8000;
lseek(desc, exe_sections[nsections - 1].raw + rsize - bw, SEEK_SET);
if(cli_readn(desc, buff, 4096) == 4096) {
if(cli_memstr(buff, 4091, "\xe8\x04\x72\x00\x00", 5)) {
*ctx->virname = dam ? "W32.Magistr.B.dam" : "W32.Magistr.B";
free(exe_sections);
return CL_VIRUS;
}
}
}
}
/* W32.Polipos.A */
if(polipos && !dll && nsections > 2 && nsections < 13 && e_lfanew <= 0x800 && (EC16(optional_hdr32.Subsystem) == 2 || EC16(optional_hdr32.Subsystem) == 3) && EC16(file_hdr.Machine) == 0x14c && optional_hdr32.SizeOfStackReserve >= 0x80000) {
uint32_t remaining = exe_sections[0].rsz;
uint32_t chunk = sizeof(buff);
uint32_t val, shift, raddr, total = 0;
const char *jpt;
struct offset_list *offlist = NULL, *offnode;
cli_dbgmsg("Detected W32.Polipos.A characteristics\n");
if(remaining < chunk)
chunk = remaining;
lseek(desc, exe_sections[0].raw, SEEK_SET);
while((bytes = cli_readn(desc, buff, chunk)) > 0) {
shift = 0;
while((uint32_t)bytes - 5 > shift) {
jpt = buff + shift;
if(*jpt!='\xe9' && *jpt!='\xe8') {
shift++;
continue;
}
val = cli_readint32(jpt + 1);
val += 5 + exe_sections[0].rva + total + shift;
raddr = cli_rawaddr(val, exe_sections, nsections, &err, fsize, hdr_size);
if(!err && (raddr >= exe_sections[polipos].raw && raddr < exe_sections[polipos].raw + exe_sections[polipos].rsz) && (!offlist || (raddr != offlist->offset))) {
offnode = (struct offset_list *) cli_malloc(sizeof(struct offset_list));
if(!offnode) {
free(exe_sections);
while(offlist) {
offnode = offlist;
offlist = offlist->next;
free(offnode);
}
return CL_EMEM;
}
offnode->offset = raddr;
offnode->next = offlist;
offlist = offnode;
}
shift++;
}
if(remaining < chunk) {
chunk = remaining;
} else {
remaining -= bytes;
if(remaining < chunk) {
chunk = remaining;
}
}
if(!remaining)
break;
total += bytes;
}
offnode = offlist;
while(offnode) {
cli_dbgmsg("Polipos: Checking offset 0x%x (%u)", offnode->offset, offnode->offset);
lseek(desc, offnode->offset, SEEK_SET);
if(cli_readn(desc, buff, 9) == 9) {
ubuff = (unsigned char *) buff;
if(ubuff[0] == 0x55 && ubuff[1] == 0x8b && ubuff[2] == 0xec &&
((ubuff[3] == 0x83 && ubuff[4] == 0xec && ubuff[6] == 0x60) || ubuff[3] == 0x60 ||
(ubuff[3] == 0x81 && ubuff[4] == 0xec && ubuff[7] == 0x00 && ubuff[8] == 0x00))) {
ret = CL_VIRUS;
*ctx->virname = "W32.Polipos.A";
break;
}
}
offnode = offnode->next;
}
while(offlist) {
offnode = offlist;
offlist = offlist->next;
free(offnode);
}
if(ret == CL_VIRUS) {
free(exe_sections);
return CL_VIRUS;
}
}
/* SUE */
if((DCONF & PE_CONF_SUE) && nsections > 2 && vep == exe_sections[nsections - 1].rva && exe_sections[nsections - 1].rsz > 0x350 && exe_sections[nsections - 1].rsz < 0x292+0x350+1000) {
char *sue=buff+0x74;
uint32_t key = 0;
if(lseek(desc, ep-4, SEEK_SET) == -1) {
cli_dbgmsg("SUE: lseek() failed\n");
free(exe_sections);
return CL_EIO;
}
if((unsigned int) cli_readn(desc, buff, exe_sections[nsections - 1].rsz+4) == exe_sections[nsections - 1].rsz+4) {
found=0;
while(CLI_ISCONTAINED(buff+4, exe_sections[nsections - 1].rsz, sue, 4*3)) {
if((cli_readint32(sue)^cli_readint32(sue+4))==0x5c41090e && (cli_readint32(sue)^cli_readint32(sue+8))==0x021e0145) {
found=1;
key=(cli_readint32(sue)^0x6e72656b);
break;
}
sue++;
}
cli_dbgmsg("SUE: key(%x) found @%x\n", key, sue-buff);
if (found && CLI_ISCONTAINED(buff, exe_sections[nsections - 1].rsz, sue-0x74, 0xbe) &&
(sue=sudecrypt(desc, fsize, exe_sections, nsections-1, sue, key, cli_readint32(buff), e_lfanew))) {
if(!(tempfile = cli_gentemp(NULL))) {
free(sue);
free(exe_sections);
return CL_EMEM;
}
if((ndesc = open(tempfile, O_RDWR|O_CREAT|O_TRUNC|O_BINARY, S_IRWXU)) < 0) {
cli_dbgmsg("sue: Can't create file %s\n", tempfile);
free(tempfile);
free(sue);
free(exe_sections);
return CL_EIO;
}
if((unsigned int) cli_writen(ndesc, sue, ep) != ep) {
cli_dbgmsg("sue: Can't write %d bytes\n", ep);
close(ndesc);
free(tempfile);
free(sue);
free(exe_sections);
return CL_EIO;
}
free(sue);
if (cli_leavetemps_flag)
cli_dbgmsg("SUE: Decrypted executable saved in %s\n", tempfile);
else
cli_dbgmsg("SUE: Executable decrypted\n");
fsync(ndesc);
lseek(ndesc, 0, SEEK_SET);
if(cli_magic_scandesc(ndesc, ctx) == CL_VIRUS) {
free(exe_sections);
close(ndesc);
if(!cli_leavetemps_flag)
unlink(tempfile);
free(tempfile);
return CL_VIRUS;
}
close(ndesc);
if(!cli_leavetemps_flag)
unlink(tempfile);
free(tempfile);
}
}
}
/* UPX, FSG, MEW support */
/* try to find the first section with physical size == 0 */
found = 0;
if(DCONF & (PE_CONF_UPX | PE_CONF_FSG | PE_CONF_MEW)) {
for(i = 0; i < (unsigned int) nsections - 1; i++) {
if(!exe_sections[i].rsz && exe_sections[i].vsz && exe_sections[i + 1].rsz && exe_sections[i + 1].vsz) {
found = 1;
cli_dbgmsg("UPX/FSG/MEW: empty section found - assuming compression\n");
break;
}
}
}
/* MEW support */
if (found && (DCONF & PE_CONF_MEW)) {
uint32_t fileoffset;
/* Check EP for MEW */
if(lseek(desc, ep, SEEK_SET) == -1) {
cli_dbgmsg("MEW: lseek() failed\n");
free(exe_sections);
return CL_EIO;
}
if((bytes = read(desc, buff, 25)) != 25 && bytes < 16) {
cli_dbgmsg("MEW: Can't read at least 16 bytes at 0x%x (%d) %d\n", ep, ep, bytes);
cli_dbgmsg("MEW: Broken or not compressed file\n");
free(exe_sections);
return CL_CLEAN;
}
fileoffset = (vep + cli_readint32(buff + 1) + 5);
do {
if (found && (buff[0] == '\xe9') && (fileoffset == 0x154 || fileoffset == 0x158))
{
uint32_t offdiff, uselzma;
cli_dbgmsg ("MEW characteristics found: %08X + %08X + 5 = %08X\n",
cli_readint32(buff + 1), vep, cli_readint32(buff + 1) + vep + 5);
if(lseek(desc, fileoffset, SEEK_SET) == -1) {
cli_dbgmsg("MEW: lseek() failed\n");
free(exe_sections);
return CL_EIO;
}
if((bytes = read(desc, buff, 0xb0)) != 0xb0) {
cli_dbgmsg("MEW: Can't read 0xb0 bytes at 0x%x (%d) %d\n", fileoffset, fileoffset, bytes);
break;
}
if (fileoffset == 0x154)
cli_dbgmsg("MEW: Win9x compatibility was set!\n");
else
cli_dbgmsg("MEW: Win9x compatibility was NOT set!\n");
/* is it always 0x1C and 0x21C or not */
if((offdiff = cli_readint32(buff+1) - EC32(optional_hdr32.ImageBase)) <= exe_sections[i + 1].rva || offdiff >= exe_sections[i + 1].rva + exe_sections[i + 1].raw - 4)
{
cli_dbgmsg("MEW: ESI is not in proper section\n");
break;
}
offdiff -= exe_sections[i + 1].rva;
if(lseek(desc, exe_sections[i + 1].raw, SEEK_SET) == -1) {
cli_dbgmsg("MEW: lseek() failed\n"); /* ACAB: lseek won't fail here but checking doesn't hurt even */
free(exe_sections);
return CL_EIO;
}
ssize = exe_sections[i + 1].vsz;
dsize = exe_sections[i].vsz;
cli_dbgmsg("MEW: ssize %08x dsize %08x offdiff: %08x\n", ssize, dsize, offdiff);
if(ctx->limits && ctx->limits->maxfilesize && (ssize + dsize > ctx->limits->maxfilesize || exe_sections[i + 1].rsz > ctx->limits->maxfilesize)) {
cli_dbgmsg("MEW: Sizes exceeded (ssize: %u, dsize: %u, max: %lu)\n", ssize, dsize , ctx->limits->maxfilesize);
free(exe_sections);
if(BLOCKMAX) {
*ctx->virname = "PE.MEW.ExceededFileSize";
return CL_VIRUS;
} else {
return CL_CLEAN;
}
}
/* allocate needed buffer */
if (!(src = cli_calloc (ssize + dsize, sizeof(char)))) {
free(exe_sections);
return CL_EMEM;
}
if (exe_sections[i + 1].rsz < offdiff + 12 || exe_sections[i + 1].rsz > ssize)
{
cli_dbgmsg("MEW: Size mismatch: %08x\n", exe_sections[i + 1].rsz);
free(src);
break;
}
if((bytes = read(desc, src + dsize, exe_sections[i + 1].rsz)) != exe_sections[i + 1].rsz) {
cli_dbgmsg("MEW: Can't read %d bytes [readed: %d]\n", exe_sections[i + 1].rsz, bytes);
free(exe_sections);
free(src);
return CL_EIO;
}
cli_dbgmsg("MEW: %d (%08x) bytes read\n", bytes, bytes);
/* count offset to lzma proc, if lzma used, 0xe8 -> call */
if (buff[0x7b] == '\xe8')
{
if (!CLI_ISCONTAINED(exe_sections[1].rva, exe_sections[1].vsz, cli_readint32(buff + 0x7c) + fileoffset + 0x80, 4))
{
cli_dbgmsg("MEW: lzma proc out of bounds!\n");
free(src);
break; /* to next unpacker in chain */
}
uselzma = cli_readint32(buff + 0x7c) - (exe_sections[0].rva - fileoffset - 0x80);
} else
uselzma = 0;
if(!(tempfile = cli_gentemp(NULL))) {
free(exe_sections);
free(src);
return CL_EMEM;
}
if((ndesc = open(tempfile, O_RDWR|O_CREAT|O_TRUNC, S_IRWXU)) < 0) {
cli_dbgmsg("MEW: Can't create file %s\n", tempfile);
free(tempfile);
free(exe_sections);
free(src);
return CL_EIO;
}
dest = src;
switch(unmew11(i, src, offdiff, ssize, dsize, EC32(optional_hdr32.ImageBase), exe_sections[0].rva, uselzma, NULL, NULL, ndesc)) {
case 1: /* Everything OK */
cli_dbgmsg("MEW: Unpacked and rebuilt executable saved in %s\n", tempfile);
free(src);
fsync(ndesc);
lseek(ndesc, 0, SEEK_SET);
cli_dbgmsg("***** Scanning rebuilt PE file *****\n");
if(cli_magic_scandesc(ndesc, ctx) == CL_VIRUS) {
free(exe_sections);
close(ndesc);
if(!cli_leavetemps_flag)
unlink(tempfile);
free(tempfile);
return CL_VIRUS;
}
close(ndesc);
if(!cli_leavetemps_flag)
unlink(tempfile);
free(tempfile);
free(exe_sections);
return CL_CLEAN;
default: /* Everything gone wrong */
cli_dbgmsg("MEW: Unpacking failed\n");
close(ndesc);
unlink(tempfile); /* It's empty anyway */
free(tempfile);
free(src);
break;
}
}
} while (0);
}
if(found || upack) {
/* Check EP for UPX vs. FSG vs. Upack */
if(lseek(desc, ep, SEEK_SET) == -1) {
cli_dbgmsg("UPX/FSG: lseek() failed\n");
free(exe_sections);
return CL_EIO;
}
if(cli_readn(desc, buff, 168) != 168) {
cli_dbgmsg("UPX/FSG: Can't read 168 bytes at 0x%x (%d)\n", ep, ep);
cli_dbgmsg("UPX/FSG: Broken or not UPX/FSG compressed file\n");
free(exe_sections);
return CL_CLEAN;
}
/* Upack 0.39 produces 2 types of executables
* 3 sections: | 2 sections (one empty, I don't chech found if !upack, since it's in OR above):
* mov esi, value | pusha
* lodsd | call $+0x9
* push eax |
*
* Upack 1.1/1.2 Beta produces [based on 2 samples (sUx) provided by aCaB]:
* 2 sections
* mov esi, value
* loads
* mov edi, eax
*
* Upack unknown [sample 0297729]
* 3 sections
* mov esi, value
* push [esi]
* jmp
*
*/
/* upack 0.39-3s + sample 0151477*/
if(((upack && nsections == 3) && /* 3 sections */
(
buff[0] == '\xbe' && cli_readint32(buff + 1) - EC32(optional_hdr32.ImageBase) > min && /* mov esi */
buff[5] == '\xad' && buff[6] == '\x50' /* lodsd; push eax */
)
||
/* based on 0297729 sample from aCaB */
(buff[0] == '\xbe' && cli_readint32(buff + 1) - EC32(optional_hdr32.ImageBase) > min && /* mov esi */
buff[5] == '\xff' && buff[6] == '\x36' /* push [esi] */
)
)
||
((!upack && nsections == 2) && /* 2 sections */
( /* upack 0.39-2s */
buff[0] == '\x60' && buff[1] == '\xe8' && cli_readint32(buff+2) == 0x9 /* pusha; call+9 */
)
||
( /* upack 1.1/1.2, based on 2 samples */
buff[0] == '\xbe' && cli_readint32(buff+1) - EC32(optional_hdr32.ImageBase) < min && /* mov esi */
cli_readint32(buff + 1) - EC32(optional_hdr32.ImageBase) > 0 &&
buff[5] == '\xad' && buff[6] == '\x8b' && buff[7] == '\xf8' /* loads; mov edi, eax */
)
)
){
uint32_t vma, off;
int a,b,c;
cli_dbgmsg("Upack characteristics found.\n");
a = exe_sections[0].vsz;
b = exe_sections[1].vsz;
if (upack) {
cli_dbgmsg("Upack: var set\n");
c = exe_sections[2].vsz;
ssize = exe_sections[0].ursz + exe_sections[0].uraw;
off = exe_sections[0].rva;
vma = EC32(optional_hdr32.ImageBase) + exe_sections[0].rva;
} else {
cli_dbgmsg("Upack: var NOT set\n");
c = exe_sections[1].rva;
ssize = exe_sections[1].uraw;
off = 0;
vma = exe_sections[1].rva - exe_sections[1].uraw;
}
dsize = a+b+c;
if (ctx->limits && ctx->limits->maxfilesize && (dsize > ctx->limits->maxfilesize || ssize > ctx->limits->maxfilesize || exe_sections[1].ursz > ctx->limits->maxfilesize))
{
cli_dbgmsg("Upack: Sizes exceeded (a: %u, b: %u, c: %ux, max: %lu)\n", a, b, c, ctx->limits->maxfilesize);
free(exe_sections);
if(BLOCKMAX) {
*ctx->virname = "PE.Upack.ExceededFileSize";
return CL_VIRUS;
} else {
return CL_CLEAN;
}
}
/* these are unsigned so if vaddr - off < 0, it should be ok */
if (exe_sections[1].rva - off > dsize || exe_sections[1].rva - off > dsize - exe_sections[1].ursz || (upack && (exe_sections[2].rva - exe_sections[0].rva > dsize || exe_sections[2].rva - exe_sections[0].rva > dsize - ssize)) || ssize > dsize)
{
cli_dbgmsg("Upack: probably malformed pe-header, skipping to next unpacker\n");
goto skip_upack_and_go_to_next_unpacker;
}
if((dest = (char *) cli_calloc(dsize, sizeof(char))) == NULL) {
free(exe_sections);
return CL_EMEM;
}
src = NULL;
lseek(desc, 0, SEEK_SET);
if(read(desc, dest, ssize) != ssize) {
cli_dbgmsg("Upack: Can't read raw data of section 0\n");
free(exe_sections);
free(dest);
return CL_EIO;
}
if (upack)
memmove(dest + exe_sections[2].rva - exe_sections[0].rva, dest, ssize);
lseek(desc, exe_sections[1].uraw, SEEK_SET);
if(read(desc, dest + exe_sections[1].rva - off, exe_sections[1].ursz) != exe_sections[1].ursz) {
cli_dbgmsg("Upack: Can't read raw data of section 1\n");
free(exe_sections);
free(dest);
return CL_EIO;
}
if(!(tempfile = cli_gentemp(NULL))) {
free(exe_sections);
free(dest);
return CL_EMEM;
}
if((ndesc = open(tempfile, O_RDWR|O_CREAT|O_TRUNC, S_IRWXU)) < 0) {
cli_dbgmsg("Upack: Can't create file %s\n", tempfile);
free(tempfile);
free(exe_sections);
free(dest);
return CL_EIO;
}
switch (unupack(upack, dest, dsize, buff, vma, ep, EC32(optional_hdr32.ImageBase), exe_sections[0].rva, ndesc))
{
case 1: /* Everything OK */
cli_dbgmsg("Upack: Unpacked and rebuilt executable saved in %s\n", tempfile);
free(dest);
fsync(ndesc);
lseek(ndesc, 0, SEEK_SET);
cli_dbgmsg("***** Scanning rebuilt PE file *****\n");
if(cli_magic_scandesc(ndesc, ctx) == CL_VIRUS) {
free(exe_sections);
close(ndesc);
if(!cli_leavetemps_flag)
unlink(tempfile);
free(tempfile);
return CL_VIRUS;
}
close(ndesc);
if(!cli_leavetemps_flag)
unlink(tempfile);
free(tempfile);
free(exe_sections);
return CL_CLEAN;
default: /* Everything gone wrong */
cli_dbgmsg("Upack: Unpacking failed\n");
close(ndesc);
unlink(tempfile); /* It's empty anyway */
free(tempfile);
free(dest);
break;
}
}
skip_upack_and_go_to_next_unpacker:
if((DCONF & PE_CONF_FSG) && buff[0] == '\x87' && buff[1] == '\x25') {
/* FSG v2.0 support - thanks to aCaB ! */
ssize = exe_sections[i + 1].rsz;
dsize = exe_sections[i].vsz;
while(found) {
uint32_t newesi, newedi, newebx, newedx;
if(ctx->limits && ctx->limits->maxfilesize && (ssize > ctx->limits->maxfilesize || dsize > ctx->limits->maxfilesize)) {
cli_dbgmsg("FSG: Sizes exceeded (ssize: %u, dsize: %u, max: %lu)\n", ssize, dsize , ctx->limits->maxfilesize);
free(exe_sections);
if(BLOCKMAX) {
*ctx->virname = "PE.FSG.ExceededFileSize";
return CL_VIRUS;
} else {
return CL_CLEAN;
}
}
if(ssize <= 0x19 || dsize <= ssize) {
cli_dbgmsg("FSG: Size mismatch (ssize: %d, dsize: %d)\n", ssize, dsize);
free(exe_sections);
return CL_CLEAN;
}
newedx = cli_readint32(buff + 2) - EC32(optional_hdr32.ImageBase);
if(!CLI_ISCONTAINED(exe_sections[i + 1].rva, exe_sections[i + 1].rsz, newedx, 4)) {
cli_dbgmsg("FSG: xchg out of bounds (%x), giving up\n", newedx);
break;
}
if((src = (char *) cli_malloc(ssize)) == NULL) {
free(exe_sections);
return CL_EMEM;
}
lseek(desc, exe_sections[i + 1].raw, SEEK_SET);
if((unsigned int) cli_readn(desc, src, ssize) != ssize) {
cli_dbgmsg("Can't read raw data of section %d\n", i + 1);
free(exe_sections);
free(src);
return CL_EIO;
}
dest = src + newedx - exe_sections[i + 1].rva;
if(newedx < exe_sections[i + 1].rva || !CLI_ISCONTAINED(src, ssize, dest, 4)) {
cli_dbgmsg("FSG: New ESP out of bounds\n");
free(src);
break;
}
newedx = cli_readint32(dest) - EC32(optional_hdr32.ImageBase);
if(!CLI_ISCONTAINED(exe_sections[i + 1].rva, exe_sections[i + 1].rsz, newedx, 4)) {
cli_dbgmsg("FSG: New ESP (%x) is wrong\n", newedx);
free(src);
break;
}
dest = src + newedx - exe_sections[i + 1].rva;
if(!CLI_ISCONTAINED(src, ssize, dest, 32)) {
cli_dbgmsg("FSG: New stack out of bounds\n");
free(src);
break;
}
newedi = cli_readint32(dest) - EC32(optional_hdr32.ImageBase);
newesi = cli_readint32(dest + 4) - EC32(optional_hdr32.ImageBase);
newebx = cli_readint32(dest + 16) - EC32(optional_hdr32.ImageBase);
newedx = cli_readint32(dest + 20);
if(newedi != exe_sections[i].rva) {
cli_dbgmsg("FSG: Bad destination buffer (edi is %x should be %x)\n", newedi, exe_sections[i].rva);
free(src);
break;
}
if(newesi < exe_sections[i + 1].rva || newesi - exe_sections[i + 1].rva >= exe_sections[i + 1].rsz) {
cli_dbgmsg("FSG: Source buffer out of section bounds\n");
free(src);
break;
}
if(!CLI_ISCONTAINED(exe_sections[i + 1].rva, exe_sections[i + 1].rsz, newebx, 16)) {
cli_dbgmsg("FSG: Array of functions out of bounds\n");
free(src);
break;
}
newedx=cli_readint32(newebx + 12 - exe_sections[i + 1].rva + src) - EC32(optional_hdr32.ImageBase);
cli_dbgmsg("FSG: found old EP @%x\n",newedx);
if((dest = (char *) cli_calloc(dsize, sizeof(char))) == NULL) {
free(exe_sections);
free(src);
return CL_EMEM;
}
if(!(tempfile = cli_gentemp(NULL))) {
free(exe_sections);
free(src);
free(dest);
return CL_EMEM;
}
if((ndesc = open(tempfile, O_RDWR|O_CREAT|O_TRUNC|O_BINARY, S_IRWXU)) < 0) {
cli_dbgmsg("FSG: Can't create file %s\n", tempfile);
free(tempfile);
free(exe_sections);
free(src);
free(dest);
return CL_EIO;
}
switch (unfsg_200(newesi - exe_sections[i + 1].rva + src, dest, ssize + exe_sections[i + 1].rva - newesi, dsize, newedi, EC32(optional_hdr32.ImageBase), newedx, ndesc)) {
case 1: /* Everything OK */
cli_dbgmsg("FSG: Unpacked and rebuilt executable saved in %s\n", tempfile);
free(src);
free(dest);
fsync(ndesc);
lseek(ndesc, 0, SEEK_SET);
cli_dbgmsg("***** Scanning rebuilt PE file *****\n");
if(cli_magic_scandesc(ndesc, ctx) == CL_VIRUS) {
free(exe_sections);
close(ndesc);
if(!cli_leavetemps_flag)
unlink(tempfile);
free(tempfile);
return CL_VIRUS;
}
close(ndesc);
if(!cli_leavetemps_flag)
unlink(tempfile);
free(tempfile);
free(exe_sections);
return CL_CLEAN;
case 0: /* We've got an unpacked buffer, no exe though */
cli_dbgmsg("FSG: Successfully decompressed\n");
close(ndesc);
unlink(tempfile);
free(tempfile);
found = 0;
upx_success = 1;
break; /* Go and scan the buffer! */
default: /* Everything gone wrong */
cli_dbgmsg("FSG: Unpacking failed\n");
close(ndesc);
unlink(tempfile); /* It's empty anyway */
free(tempfile);
free(src);
free(dest);
break;
}
break; /* were done with 2 */
}
}
if(found && (DCONF & PE_CONF_FSG) && buff[0] == '\xbe' && cli_readint32(buff + 1) - EC32(optional_hdr32.ImageBase) < min) {
/* FSG support - v. 1.33 (thx trog for the many samples) */
ssize = exe_sections[i + 1].rsz;
dsize = exe_sections[i].vsz;
while(found) {
int sectcnt = 0;
char *support;
uint32_t newesi, newedi, newebx, oldep, gp, t;
struct cli_exe_section *sections;
if(ctx->limits && ctx->limits->maxfilesize && (ssize > ctx->limits->maxfilesize || dsize > ctx->limits->maxfilesize)) {
cli_dbgmsg("FSG: Sizes exceeded (ssize: %u, dsize: %u, max: %lu)\n", ssize, dsize, ctx->limits->maxfilesize);
free(exe_sections);
if(BLOCKMAX) {
*ctx->virname = "PE.FSG.ExceededFileSize";
return CL_VIRUS;
} else {
return CL_CLEAN;
}
}
if(ssize <= 0x19 || dsize <= ssize) {
cli_dbgmsg("FSG: Size mismatch (ssize: %d, dsize: %d)\n", ssize, dsize);
free(exe_sections);
return CL_CLEAN;
}
if(!(gp = cli_rawaddr(cli_readint32(buff + 1) - EC32(optional_hdr32.ImageBase), NULL, 0 , &err, fsize, hdr_size)) && err ) {
cli_dbgmsg("FSG: Support data out of padding area\n");
break;
}
lseek(desc, gp, SEEK_SET);
gp = exe_sections[i + 1].raw - gp;
if(ctx->limits && ctx->limits->maxfilesize && (unsigned int) gp > ctx->limits->maxfilesize) {
cli_dbgmsg("FSG: Buffer size exceeded (size: %d, max: %lu)\n", gp, ctx->limits->maxfilesize);
free(exe_sections);
if(BLOCKMAX) {
*ctx->virname = "PE.FSG.ExceededFileSize";
return CL_VIRUS;
} else {
return CL_CLEAN;
}
}
if((support = (char *) cli_malloc(gp)) == NULL) {
free(exe_sections);
return CL_EMEM;
}
if((int)cli_readn(desc, support, gp) != (int)gp) {
cli_dbgmsg("Can't read %d bytes from padding area\n", gp);
free(exe_sections);
free(support);
return CL_EIO;
}
/* newebx = cli_readint32(support) - EC32(optional_hdr32.ImageBase); Unused */
newedi = cli_readint32(support + 4) - EC32(optional_hdr32.ImageBase); /* 1st dest */
newesi = cli_readint32(support + 8) - EC32(optional_hdr32.ImageBase); /* Source */
if(newesi < exe_sections[i + 1].rva || newesi - exe_sections[i + 1].rva >= exe_sections[i + 1].rsz) {
cli_dbgmsg("FSG: Source buffer out of section bounds\n");
free(support);
break;
}
if(newedi != exe_sections[i].rva) {
cli_dbgmsg("FSG: Bad destination (is %x should be %x)\n", newedi, exe_sections[i].rva);
free(support);
break;
}
/* Counting original sections */
for(t = 12; t < gp - 4; t += 4) {
uint32_t rva = cli_readint32(support+t);
if(!rva)
break;
rva -= EC32(optional_hdr32.ImageBase)+1;
sectcnt++;
if(rva % 0x1000)
/* FIXME: really need to bother? */
cli_dbgmsg("FSG: Original section %d is misaligned\n", sectcnt);
if(rva < exe_sections[i].rva || rva - exe_sections[i].rva >= exe_sections[i].vsz) {
cli_dbgmsg("FSG: Original section %d is out of bounds\n", sectcnt);
break;
}
}
if(t >= gp - 4 || cli_readint32(support + t)) {
free(support);
break;
}
if((sections = (struct cli_exe_section *) cli_malloc((sectcnt + 1) * sizeof(struct cli_exe_section))) == NULL) {
free(exe_sections);
free(support);
return CL_EMEM;
}
sections[0].rva = newedi;
for(t = 1; t <= (uint32_t)sectcnt; t++)
sections[t].rva = cli_readint32(support + 8 + t * 4) - 1 - EC32(optional_hdr32.ImageBase);
free(support);
if((src = (char *) cli_malloc(ssize)) == NULL) {
free(exe_sections);
free(sections);
return CL_EMEM;
}
lseek(desc, exe_sections[i + 1].raw, SEEK_SET);
if((unsigned int) cli_readn(desc, src, ssize) != ssize) {
cli_dbgmsg("Can't read raw data of section %d\n", i);
free(exe_sections);
free(sections);
free(src);
return CL_EIO;
}
if((dest = (char *) cli_calloc(dsize, sizeof(char))) == NULL) {
free(exe_sections);
free(src);
free(sections);
return CL_EMEM;
}
oldep = vep + 161 + 6 + cli_readint32(buff+163);
cli_dbgmsg("FSG: found old EP @%x\n", oldep);
if(!(tempfile = cli_gentemp(NULL))) {
free(exe_sections);
free(src);
free(dest);
free(sections);
return CL_EMEM;
}
if((ndesc = open(tempfile, O_RDWR|O_CREAT|O_TRUNC|O_BINARY, S_IRWXU)) < 0) {
cli_dbgmsg("FSG: Can't create file %s\n", tempfile);
free(tempfile);
free(exe_sections);
free(src);
free(dest);
free(sections);
return CL_EIO;
}
switch(unfsg_133(src + newesi - exe_sections[i + 1].rva, dest, ssize + exe_sections[i + 1].rva - newesi, dsize, sections, sectcnt, EC32(optional_hdr32.ImageBase), oldep, ndesc)) {
case 1: /* Everything OK */
cli_dbgmsg("FSG: Unpacked and rebuilt executable saved in %s\n", tempfile);
free(src);
free(dest);
free(sections);
fsync(ndesc);
lseek(ndesc, 0, SEEK_SET);
cli_dbgmsg("***** Scanning rebuilt PE file *****\n");
if(cli_magic_scandesc(ndesc, ctx) == CL_VIRUS) {
free(exe_sections);
close(ndesc);
if(!cli_leavetemps_flag)
unlink(tempfile);
free(tempfile);
return CL_VIRUS;
}
close(ndesc);
if(!cli_leavetemps_flag)
unlink(tempfile);
free(tempfile);
free(exe_sections);
return CL_CLEAN;
case 0: /* We've got an unpacked buffer, no exe though */
cli_dbgmsg("FSG: Successfully decompressed\n");
close(ndesc);
unlink(tempfile);
free(tempfile);
free(sections);
found = 0;
upx_success = 1;
break; /* Go and scan the buffer! */
default: /* Everything gone wrong */
cli_dbgmsg("FSG: Unpacking failed\n");
close(ndesc);
unlink(tempfile); /* It's empty anyway */
free(tempfile);
free(src);
free(dest);
free(sections);
break;
}
break; /* were done with 1.33 */
}
}
/* FIXME: easy 2 hack */
if(found && (DCONF & PE_CONF_FSG) && buff[0] == '\xbb' && cli_readint32(buff + 1) - EC32(optional_hdr32.ImageBase) < min && buff[5] == '\xbf' && buff[10] == '\xbe' && vep >= exe_sections[i + 1].rva && vep - exe_sections[i + 1].rva > exe_sections[i + 1].rva - 0xe0 ) {
/* FSG support - v. 1.31 */
ssize = exe_sections[i + 1].rsz;
dsize = exe_sections[i].vsz;
while(found) {
int sectcnt = 0;
uint32_t t;
uint32_t gp = cli_rawaddr(cli_readint32(buff+1) - EC32(optional_hdr32.ImageBase), NULL, 0 , &err, fsize, hdr_size);
char *support;
uint32_t newesi = cli_readint32(buff+11) - EC32(optional_hdr32.ImageBase);
uint32_t newedi = cli_readint32(buff+6) - EC32(optional_hdr32.ImageBase);
uint32_t oldep = vep - exe_sections[i + 1].rva;
struct cli_exe_section *sections;
if(err) {
cli_dbgmsg("FSG: Support data out of padding area\n");
break;
}
if(newesi < exe_sections[i + 1].rva || newesi - exe_sections[i + 1].rva >= exe_sections[i + 1].raw) {
cli_dbgmsg("FSG: Source buffer out of section bounds\n");
break;
}
if(newedi != exe_sections[i].rva) {
cli_dbgmsg("FSG: Bad destination (is %x should be %x)\n", newedi, exe_sections[i].rva);
break;
}
if(ctx->limits && ctx->limits->maxfilesize && (ssize > ctx->limits->maxfilesize || dsize > ctx->limits->maxfilesize)) {
cli_dbgmsg("FSG: Sizes exceeded (ssize: %u, dsize: %u, max: %lu)\n", ssize, dsize, ctx->limits->maxfilesize);
free(exe_sections);
if(BLOCKMAX) {
*ctx->virname = "PE.FSG.ExceededFileSize";
return CL_VIRUS;
} else {
return CL_CLEAN;
}
}
if(ssize <= 0x19 || dsize <= ssize) {
cli_dbgmsg("FSG: Size mismatch (ssize: %d, dsize: %d)\n", ssize, dsize);
free(exe_sections);
return CL_CLEAN;
}
lseek(desc, gp, SEEK_SET);
gp = exe_sections[i + 1].raw - gp;
if(ctx->limits && ctx->limits->maxfilesize && gp > ctx->limits->maxfilesize) {
cli_dbgmsg("FSG: Buffer size exceeded (size: %d, max: %lu)\n", gp, ctx->limits->maxfilesize);
free(exe_sections);
if(BLOCKMAX) {
*ctx->virname = "PE.FSG.ExceededFileSize";
return CL_VIRUS;
} else {
return CL_CLEAN;
}
}
if((support = (char *) cli_malloc(gp)) == NULL) {
free(exe_sections);
return CL_EMEM;
}
if(cli_readn(desc, support, gp) != (int)gp) {
cli_dbgmsg("Can't read %d bytes from padding area\n", gp);
free(exe_sections);
free(support);
return CL_EIO;
}
/* Counting original sections */
for(t = 0; t < gp - 2; t += 2) {
uint32_t rva = support[t]|(support[t+1]<<8);
if (rva == 2 || rva == 1)
break;
rva = ((rva-2)<<12) - EC32(optional_hdr32.ImageBase);
sectcnt++;
if(rva < exe_sections[i].rva || rva - exe_sections[i].rva >= exe_sections[i].vsz) {
cli_dbgmsg("FSG: Original section %d is out of bounds\n", sectcnt);
break;
}
}
if(t >= gp-10 || cli_readint32(support + t + 6) != 2) {
free(support);
break;
}
if((sections = (struct cli_exe_section *) cli_malloc((sectcnt + 1) * sizeof(struct cli_exe_section))) == NULL) {
free(exe_sections);
free(support);
return CL_EMEM;
}
sections[0].rva = newedi;
for(t = 0; t <= (uint32_t)sectcnt - 1; t++) {
sections[t+1].rva = (((support[t*2]|(support[t*2+1]<<8))-2)<<12)-EC32(optional_hdr32.ImageBase);
}
free(support);
if((src = (char *) cli_malloc(ssize)) == NULL) {
free(exe_sections);
free(sections);
return CL_EMEM;
}
lseek(desc, exe_sections[i + 1].raw, SEEK_SET);
if((unsigned int) cli_readn(desc, src, ssize) != ssize) {
cli_dbgmsg("FSG: Can't read raw data of section %d\n", i);
free(exe_sections);
free(sections);
free(src);
return CL_EIO;
}
if((dest = (char *) cli_calloc(dsize, sizeof(char))) == NULL) {
free(exe_sections);
free(src);
free(sections);
return CL_EMEM;
}
/* Better not increasing buff size any further, let's go the hard way */
gp = 0xda + 6*(buff[16]=='\xe8');
oldep = vep + gp + 6 + cli_readint32(src+gp+2+oldep);
cli_dbgmsg("FSG: found old EP @%x\n", oldep);
if(!(tempfile = cli_gentemp(NULL))) {
free(exe_sections);
free(src);
free(dest);
free(sections);
return CL_EMEM;
}
if((ndesc = open(tempfile, O_RDWR|O_CREAT|O_TRUNC|O_BINARY, S_IRWXU)) < 0) {
cli_dbgmsg("FSG: Can't create file %s\n", tempfile);
free(tempfile);
free(exe_sections);
free(src);
free(dest);
free(sections);
return CL_EIO;
}
switch(unfsg_133(src + newesi - exe_sections[i + 1].rva, dest, ssize + exe_sections[i + 1].rva - newesi, dsize, sections, sectcnt, EC32(optional_hdr32.ImageBase), oldep, ndesc)) {
case 1: /* Everything OK */
cli_dbgmsg("FSG: Unpacked and rebuilt executable saved in %s\n", tempfile);
free(src);
free(dest);
free(sections);
fsync(ndesc);
lseek(ndesc, 0, SEEK_SET);
cli_dbgmsg("***** Scanning rebuilt PE file *****\n");
if(cli_magic_scandesc(ndesc, ctx) == CL_VIRUS) {
free(exe_sections);
close(ndesc);
if(!cli_leavetemps_flag)
unlink(tempfile);
free(tempfile);
return CL_VIRUS;
}
close(ndesc);
if(!cli_leavetemps_flag)
unlink(tempfile);
free(tempfile);
free(exe_sections);
return CL_CLEAN;
case 0: /* We've got an unpacked buffer, no exe though */
cli_dbgmsg("FSG: FSG: Successfully decompressed\n");
close(ndesc);
unlink(tempfile);
free(tempfile);
free(sections);
found = 0;
upx_success = 1;
break; /* Go and scan the buffer! */
default: /* Everything gone wrong */
cli_dbgmsg("FSG: Unpacking failed\n");
close(ndesc);
unlink(tempfile); /* It's empty anyway */
free(tempfile);
free(src);
free(dest);
free(sections);
break;
}
break; /* were done with 1.31 */
}
}
if(found && (DCONF & PE_CONF_UPX)) {
/* UPX support */
/* we assume (i + 1) is UPX1 */
ssize = exe_sections[i + 1].rsz;
dsize = exe_sections[i].vsz + exe_sections[i + 1].vsz;
if(ctx->limits && ctx->limits->maxfilesize && (ssize > ctx->limits->maxfilesize || dsize > ctx->limits->maxfilesize)) {
cli_dbgmsg("UPX: Sizes exceeded (ssize: %u, dsize: %u, max: %lu)\n", ssize, dsize , ctx->limits->maxfilesize);
free(exe_sections);
if(BLOCKMAX) {
*ctx->virname = "PE.UPX.ExceededFileSize";
return CL_VIRUS;
} else {
return CL_CLEAN;
}
}
if(ssize <= 0x19 || dsize <= ssize) { /* FIXME: What are reasonable values? */
cli_dbgmsg("UPX: Size mismatch (ssize: %d, dsize: %d)\n", ssize, dsize);
free(exe_sections);
return CL_CLEAN;
}
if((src = (char *) cli_malloc(ssize)) == NULL) {
free(exe_sections);
return CL_EMEM;
}
if(dsize > CLI_MAX_ALLOCATION) {
cli_errmsg("UPX: Too big value of dsize\n");
free(exe_sections);
free(src);
return CL_EMEM;
}
if((dest = (char *) cli_calloc(dsize + 8192, sizeof(char))) == NULL) {
free(exe_sections);
free(src);
return CL_EMEM;
}
lseek(desc, exe_sections[i + 1].raw, SEEK_SET);
if((unsigned int) cli_readn(desc, src, ssize) != ssize) {
cli_dbgmsg("UPX: Can't read raw data of section %d\n", i+1);
free(exe_sections);
free(src);
free(dest);
return CL_EIO;
}
/* try to detect UPX code */
if(lseek(desc, ep, SEEK_SET) == -1) {
cli_dbgmsg("UPX: lseek() failed\n");
free(exe_sections);
free(src);
free(dest);
return CL_EIO;
}
if(cli_readn(desc, buff, 126) != 126) { /* i.e. 0x69 + 13 + 8 */
cli_dbgmsg("UPX: Can't read 126 bytes at 0x%x (%d)\n", ep, ep);
cli_dbgmsg("UPX: Broken or not UPX compressed file\n");
free(exe_sections);
free(src);
free(dest);
return CL_CLEAN;
} else {
if(cli_memstr(UPX_NRV2B, 24, buff + 0x69, 13) || cli_memstr(UPX_NRV2B, 24, buff + 0x69 + 8, 13)) {
cli_dbgmsg("UPX: Looks like a NRV2B decompression routine\n");
upxfn = upx_inflate2b;
} else if(cli_memstr(UPX_NRV2D, 24, buff + 0x69, 13) || cli_memstr(UPX_NRV2D, 24, buff + 0x69 + 8, 13)) {
cli_dbgmsg("UPX: Looks like a NRV2D decompression routine\n");
upxfn = upx_inflate2d;
} else if(cli_memstr(UPX_NRV2E, 24, buff + 0x69, 13) || cli_memstr(UPX_NRV2E, 24, buff + 0x69 + 8, 13)) {
cli_dbgmsg("UPX: Looks like a NRV2E decompression routine\n");
upxfn = upx_inflate2e;
}
}
if(upxfn) {
int skew = cli_readint32(buff + 2) - EC32(optional_hdr32.ImageBase) - exe_sections[i + 1].rva;
if(buff[1] != '\xbe' || skew <= 0 || skew > 0xfff) { /* FIXME: legit skews?? */
skew = 0;
if(upxfn(src, ssize, dest, &dsize, exe_sections[i].rva, exe_sections[i + 1].rva, vep) >= 0)
upx_success = 1;
} else {
cli_dbgmsg("UPX: UPX1 seems skewed by %d bytes\n", skew);
if(upxfn(src + skew, ssize - skew, dest, &dsize, exe_sections[i].rva, exe_sections[i + 1].rva, vep-skew) >= 0 || upxfn(src, ssize, dest, &dsize, exe_sections[i].rva, exe_sections[i + 1].rva, vep) >= 0)
upx_success = 1;
}
if(upx_success)
cli_dbgmsg("UPX: Successfully decompressed\n");
else
cli_dbgmsg("UPX: Preferred decompressor failed\n");
}
if(!upx_success && upxfn != upx_inflate2b) {
if(upx_inflate2b(src, ssize, dest, &dsize, exe_sections[i].rva, exe_sections[i + 1].rva, vep) == -1 && upx_inflate2b(src + 0x15, ssize - 0x15, dest, &dsize, exe_sections[i].rva, exe_sections[i + 1].rva, vep - 0x15) == -1) {
cli_dbgmsg("UPX: NRV2B decompressor failed\n");
} else {
upx_success = 1;
cli_dbgmsg("UPX: Successfully decompressed with NRV2B\n");
}
}
if(!upx_success && upxfn != upx_inflate2d) {
if(upx_inflate2d(src, ssize, dest, &dsize, exe_sections[i].rva, exe_sections[i + 1].rva, vep) == -1 && upx_inflate2d(src + 0x15, ssize - 0x15, dest, &dsize, exe_sections[i].rva, exe_sections[i + 1].rva, vep - 0x15) == -1) {
cli_dbgmsg("UPX: NRV2D decompressor failed\n");
} else {
upx_success = 1;
cli_dbgmsg("UPX: Successfully decompressed with NRV2D\n");
}
}
if(!upx_success && upxfn != upx_inflate2e) {
if(upx_inflate2e(src, ssize, dest, &dsize, exe_sections[i].rva, exe_sections[i + 1].rva, vep) == -1 && upx_inflate2e(src + 0x15, ssize - 0x15, dest, &dsize, exe_sections[i].rva, exe_sections[i + 1].rva, vep - 0x15) == -1) {
cli_dbgmsg("UPX: NRV2E decompressor failed\n");
} else {
upx_success = 1;
cli_dbgmsg("UPX: Successfully decompressed with NRV2E\n");
}
}
if(!upx_success) {
cli_dbgmsg("UPX: All decompressors failed\n");
free(src);
free(dest);
}
}
if(upx_success) {
free(src);
free(exe_sections);
if(!(tempfile = cli_gentemp(NULL))) {
free(dest);
return CL_EMEM;
}
if((ndesc = open(tempfile, O_RDWR|O_CREAT|O_TRUNC|O_BINARY, S_IRWXU)) < 0) {
cli_dbgmsg("UPX/FSG: Can't create file %s\n", tempfile);
free(tempfile);
free(dest);
return CL_EIO;
}
if((unsigned int) write(ndesc, dest, dsize) != dsize) {
cli_dbgmsg("UPX/FSG: Can't write %d bytes\n", dsize);
free(tempfile);
free(dest);
close(ndesc);
return CL_EIO;
}
free(dest);
fsync(ndesc);
lseek(ndesc, 0, SEEK_SET);
if(cli_leavetemps_flag)
cli_dbgmsg("UPX/FSG: Decompressed data saved in %s\n", tempfile);
cli_dbgmsg("***** Scanning decompressed file *****\n");
if((ret = cli_magic_scandesc(ndesc, ctx)) == CL_VIRUS) {
close(ndesc);
if(!cli_leavetemps_flag)
unlink(tempfile);
free(tempfile);
return CL_VIRUS;
}
close(ndesc);
if(!cli_leavetemps_flag)
unlink(tempfile);
free(tempfile);
return ret;
}
}
/* Petite */
found = 2;
lseek(desc, ep, SEEK_SET);
memset(buff, 0, sizeof(buff));
if(cli_readn(desc, buff, 200) == -1) {
cli_dbgmsg("cli_readn() failed\n");
free(exe_sections);
return CL_EIO;
}
if(buff[0] != '\xb8' || (uint32_t) cli_readint32(buff + 1) != exe_sections[nsections - 1].rva + EC32(optional_hdr32.ImageBase)) {
if(nsections < 2 || buff[0] != '\xb8' || (uint32_t) cli_readint32(buff + 1) != exe_sections[nsections - 2].rva + EC32(optional_hdr32.ImageBase))
found = 0;
else
found = 1;
}
if((DCONF & PE_CONF_PETITE) && found) {
cli_dbgmsg("Petite: v2.%d compression detected\n", found);
if(cli_readint32(buff + 0x80) == 0x163c988d) {
cli_dbgmsg("Petite: level zero compression is not supported yet\n");
} else {
dsize = max - min;
if(ctx->limits && ctx->limits->maxfilesize && dsize > ctx->limits->maxfilesize) {
cli_dbgmsg("Petite: Size exceeded (dsize: %u, max: %lu)\n", dsize, ctx->limits->maxfilesize);
free(exe_sections);
if(BLOCKMAX) {
*ctx->virname = "PE.Petite.ExceededFileSize";
return CL_VIRUS;
} else {
return CL_CLEAN;
}
}
if((dest = (char *) cli_calloc(dsize, sizeof(char))) == NULL) {
cli_dbgmsg("Petite: Can't allocate %d bytes\n", dsize);
free(exe_sections);
return CL_EMEM;
}
for(i = 0 ; i < nsections; i++) {
if(exe_sections[i].raw) {
uint32_t offset = exe_sections[i].raw;
if(lseek(desc, offset, SEEK_SET) == -1 || (unsigned int) cli_readn(desc, dest + exe_sections[i].rva - min, exe_sections[i].ursz) != exe_sections[i].ursz) {
free(exe_sections);
free(dest);
return CL_EIO;
}
}
}
if(!(tempfile = cli_gentemp(NULL))) {
free(dest);
free(exe_sections);
return CL_EMEM;
}
if((ndesc = open(tempfile, O_RDWR|O_CREAT|O_TRUNC|O_BINARY, S_IRWXU)) < 0) {
cli_dbgmsg("Petite: Can't create file %s\n", tempfile);
free(tempfile);
free(exe_sections);
free(dest);
return CL_EIO;
}
/* aCaB: Fixed to allow petite v2.1 unpacking (last section is a ghost) */
if (!petite_inflate2x_1to9(dest, min, max - min, exe_sections,
nsections - (found == 1 ? 1 : 0), EC32(optional_hdr32.ImageBase),
vep, ndesc, found, EC32(optional_hdr32.DataDirectory[2].VirtualAddress),
EC32(optional_hdr32.DataDirectory[2].Size))) {
cli_dbgmsg("Petite: Unpacked and rebuilt executable saved in %s\n", tempfile);
cli_dbgmsg("***** Scanning rebuilt PE file *****\n");
free(dest);
fsync(ndesc);
lseek(ndesc, 0, SEEK_SET);
if(cli_magic_scandesc(ndesc, ctx) == CL_VIRUS) {
free(exe_sections);
close(ndesc);
if(!cli_leavetemps_flag) {
unlink(tempfile);
}
free(tempfile);
return CL_VIRUS;
}
} else {
cli_dbgmsg("Petite: Unpacking failed\n");
free(dest);
}
close(ndesc);
if(!cli_leavetemps_flag) {
unlink(tempfile);
}
free(tempfile);
}
}
/* PESpin 1.1 */
if((DCONF & PE_CONF_PESPIN) && nsections > 1 &&
vep >= exe_sections[nsections - 1].rva &&
vep < exe_sections[nsections - 1].rva + exe_sections[nsections - 1].rsz - 0x3217 - 4 &&
memcmp(buff+4, "\xe8\x00\x00\x00\x00\x8b\x1c\x24\x83\xc3", 10) == 0) {
char *spinned;
if(ctx->limits && ctx->limits->maxfilesize && fsize > ctx->limits->maxfilesize) {
cli_dbgmsg("PEspin: Size exceeded (fsize: %u, max: %lu)\n", fsize, ctx->limits->maxfilesize);
free(exe_sections);
if(BLOCKMAX) {
*ctx->virname = "PE.Pespin.ExceededFileSize";
return CL_VIRUS;
} else {
return CL_CLEAN;
}
}
if((spinned = (char *) cli_malloc(fsize)) == NULL) {
free(exe_sections);
return CL_EMEM;
}
lseek(desc, 0, SEEK_SET);
if((size_t) cli_readn(desc, spinned, fsize) != fsize) {
cli_dbgmsg("PESpin: Can't read %d bytes\n", fsize);
free(spinned);
free(exe_sections);
return CL_EIO;
}
if(!(tempfile = cli_gentemp(NULL))) {
free(spinned);
free(exe_sections);
return CL_EMEM;
}
if((ndesc = open(tempfile, O_RDWR|O_CREAT|O_TRUNC|O_BINARY, S_IRWXU)) < 0) {
cli_dbgmsg("PESpin: Can't create file %s\n", tempfile);
free(tempfile);
free(spinned);
free(exe_sections);
return CL_EIO;
}
switch(unspin(spinned, fsize, exe_sections, nsections - 1, vep, ndesc, ctx)) {
case 0:
free(spinned);
if(cli_leavetemps_flag)
cli_dbgmsg("PESpin: Unpacked and rebuilt executable saved in %s\n", tempfile);
else
cli_dbgmsg("PESpin: Unpacked and rebuilt executable\n");
fsync(ndesc);
lseek(ndesc, 0, SEEK_SET);
if(cli_magic_scandesc(ndesc, ctx) == CL_VIRUS) {
close(ndesc);
if(!cli_leavetemps_flag)
unlink(tempfile);
free(tempfile);
free(exe_sections);
return CL_VIRUS;
}
close(ndesc);
if(!cli_leavetemps_flag)
unlink(tempfile);
break;
case 1:
free(spinned);
close(ndesc);
unlink(tempfile);
cli_dbgmsg("PESpin: Rebuilding failed\n");
break;
case 2:
free(spinned);
close(ndesc);
unlink(tempfile);
cli_dbgmsg("PESpin: Size exceeded\n");
if(BLOCKMAX) {
free(tempfile);
free(exe_sections);
*ctx->virname = "PE.Pespin.ExceededFileSize";
return CL_VIRUS;
}
}
free(tempfile);
}
/* yC 1.3 */
if((DCONF & PE_CONF_YC) && nsections > 1 &&
EC32(optional_hdr32.AddressOfEntryPoint) == exe_sections[nsections - 1].rva + 0x60 &&
memcmp(buff, "\x55\x8B\xEC\x53\x56\x57\x60\xE8\x00\x00\x00\x00\x5D\x81\xED\x6C\x28\x40\x00\xB9\x5D\x34\x40\x00\x81\xE9\xC6\x28\x40\x00\x8B\xD5\x81\xC2\xC6\x28\x40\x00\x8D\x3A\x8B\xF7\x33\xC0\xEB\x04\x90\xEB\x01\xC2\xAC", 51) == 0) {
char *spinned;
if ( fsize >= exe_sections[nsections - 1].raw + 0xC6 + 0xb97 ) { /* size check on yC sect */
if((spinned = (char *) cli_malloc(fsize)) == NULL) {
free(exe_sections);
return CL_EMEM;
}
lseek(desc, 0, SEEK_SET);
if((size_t) cli_readn(desc, spinned, fsize) != fsize) {
cli_dbgmsg("yC: Can't read %d bytes\n", fsize);
free(spinned);
free(exe_sections);
return CL_EIO;
}
if(!(tempfile = cli_gentemp(NULL))) {
free(spinned);
free(exe_sections);
return CL_EMEM;
}
if((ndesc = open(tempfile, O_RDWR|O_CREAT|O_TRUNC|O_BINARY, S_IRWXU)) < 0) {
cli_dbgmsg("yC: Can't create file %s\n", tempfile);
free(tempfile);
free(spinned);
free(exe_sections);
return CL_EIO;
}
if(!yc_decrypt(spinned, fsize, exe_sections, nsections-1, e_lfanew, ndesc)) {
free(spinned);
cli_dbgmsg("yC: Unpacked and rebuilt executable saved in %s\n", tempfile);
fsync(ndesc);
lseek(ndesc, 0, SEEK_SET);
if(cli_magic_scandesc(ndesc, ctx) == CL_VIRUS) {
free(exe_sections);
close(ndesc);
if(!cli_leavetemps_flag) {
unlink(tempfile);
free(tempfile);
} else {
free(tempfile);
}
return CL_VIRUS;
}
} else {
free(spinned);
cli_dbgmsg("yC: Rebuilding failed\n");
}
close(ndesc);
if(!cli_leavetemps_flag) {
unlink(tempfile);
free(tempfile);
} else {
free(tempfile);
}
}
}
/* WWPack */
if((DCONF & PE_CONF_WWPACK) && nsections > 1 &&
exe_sections[nsections-1].raw>0x2b1 &&
vep == exe_sections[nsections - 1].rva &&
exe_sections[nsections - 1].rva + exe_sections[nsections - 1].rsz == max &&
memcmp(buff, "\x53\x55\x8b\xe8\x33\xdb\xeb", 7) == 0 &&
memcmp(buff+0x68, "\xe8\x00\x00\x00\x00\x58\x2d\x6d\x00\x00\x00\x50\x60\x33\xc9\x50\x58\x50\x50", 19) == 0) {
uint32_t headsize=exe_sections[nsections - 1].raw;
char *dest, *wwp;
for(i = 0 ; i < (unsigned int)nsections-1; i++)
if (!err && exe_sections[i].raw<headsize) headsize=exe_sections[i].raw;
dsize = max-min+headsize-exe_sections[nsections - 1].rsz;
if(ctx->limits && ctx->limits->maxfilesize && dsize > ctx->limits->maxfilesize) {
cli_dbgmsg("WWPack: Size exceeded (dsize: %u, max: %lu)\n", dsize, ctx->limits->maxfilesize);
free(exe_sections);
if(BLOCKMAX) {
*ctx->virname = "PE.WWPack.ExceededFileSize";
return CL_VIRUS;
} else {
return CL_CLEAN;
}
}
if((dest = (char *) cli_calloc(dsize, sizeof(char))) == NULL) {
cli_dbgmsg("WWPack: Can't allocate %d bytes\n", dsize);
free(exe_sections);
return CL_EMEM;
}
lseek(desc, 0, SEEK_SET);
if((size_t) cli_readn(desc, dest, headsize) != headsize) {
cli_dbgmsg("WWPack: Can't read %d bytes from headers\n", headsize);
free(dest);
free(exe_sections);
return CL_EIO;
}
for(i = 0 ; i < (unsigned int)nsections-1; i++) {
if(exe_sections[i].rsz) {
uint32_t offset = exe_sections[i].raw;
if(err || lseek(desc, offset, SEEK_SET) == -1 || (unsigned int) cli_readn(desc, dest + headsize + exe_sections[i].rva - min, exe_sections[i].rsz) != exe_sections[i].rsz) {
free(dest);
free(exe_sections);
return CL_EIO;
}
}
}
if((wwp = (char *) cli_calloc(exe_sections[nsections - 1].rsz, sizeof(char))) == NULL) {
cli_dbgmsg("WWPack: Can't allocate %d bytes\n", exe_sections[nsections - 1].rsz);
free(dest);
free(exe_sections);
return CL_EMEM;
}
lseek(desc, exe_sections[nsections - 1].raw, SEEK_SET);
if((size_t) cli_readn(desc, wwp, exe_sections[nsections - 1].rsz) != exe_sections[nsections - 1].rsz) {
cli_dbgmsg("WWPack: Can't read %d bytes from wwpack sect\n", exe_sections[nsections - 1].rsz);
free(dest);
free(wwp);
free(exe_sections);
return CL_EIO;
}
if (!wwunpack(dest, dsize, headsize, min, exe_sections[nsections-1].rva, e_lfanew, wwp, exe_sections[nsections - 1].rsz, nsections-1)) {
free(wwp);
if(!(tempfile = cli_gentemp(NULL))) {
free(dest);
free(exe_sections);
return CL_EMEM;
}
if((ndesc = open(tempfile, O_RDWR|O_CREAT|O_TRUNC|O_BINARY, S_IRWXU)) < 0) {
cli_dbgmsg("WWPack: Can't create file %s\n", tempfile);
free(tempfile);
free(dest);
free(exe_sections);
return CL_EIO;
}
if((unsigned int) write(ndesc, dest, dsize) != dsize) {
cli_dbgmsg("WWPack: Can't write %d bytes\n", dsize);
close(ndesc);
free(tempfile);
free(dest);
free(exe_sections);
return CL_EIO;
}
free(dest);
if (cli_leavetemps_flag)
cli_dbgmsg("WWPack: Unpacked and rebuilt executable saved in %s\n", tempfile);
else
cli_dbgmsg("WWPack: Unpacked and rebuilt executable\n");
fsync(ndesc);
lseek(ndesc, 0, SEEK_SET);
if(cli_magic_scandesc(ndesc, ctx) == CL_VIRUS) {
free(exe_sections);
close(ndesc);
if(!cli_leavetemps_flag)
unlink(tempfile);
free(tempfile);
return CL_VIRUS;
}
close(ndesc);
if(!cli_leavetemps_flag)
unlink(tempfile);
free(tempfile);
} else {
free(wwp);
free(dest);
cli_dbgmsg("WWPpack: Decompression failed\n");
}
}
/* NsPack */
while (DCONF & PE_CONF_NSPACK) {
uint32_t eprva = vep;
uint32_t start_of_stuff, ssize, dsize, rep = ep;
unsigned int nowinldr;
char nbuff[24];
char *src=buff, *dest;
if (*buff=='\xe9') { /* bitched headers */
eprva = cli_readint32(buff+1)+vep+5;
if (!(rep = cli_rawaddr(eprva, exe_sections, nsections, &err, fsize, hdr_size)) && err) break;
if (lseek(desc, rep, SEEK_SET)==-1) break;
if (cli_readn(desc, nbuff, 24)!=24) break;
src = nbuff;
}
if (memcmp(src, "\x9c\x60\xe8\x00\x00\x00\x00\x5d\xb8\x07\x00\x00\x00", 13)) break;
nowinldr = 0x54-cli_readint32(src+17);
cli_dbgmsg("NsPack: Found *start_of_stuff @delta-%x\n", nowinldr);
if (lseek(desc, rep-nowinldr, SEEK_SET)==-1) break;
if (cli_readn(desc, nbuff, 4)!=4) break;
start_of_stuff=rep+cli_readint32(nbuff);
if (lseek(desc, start_of_stuff, SEEK_SET)==-1) break;
if (cli_readn(desc, nbuff, 20)!=20) break;
src = nbuff;
if (!cli_readint32(nbuff)) {
start_of_stuff+=4; /* FIXME: more to do */
src+=4;
}
ssize = cli_readint32(src+5)|0xff;
dsize = cli_readint32(src+9);
if(ctx->limits && ctx->limits->maxfilesize && (ssize > ctx->limits->maxfilesize || dsize > ctx->limits->maxfilesize)) {
cli_dbgmsg("NsPack: Size exceeded\n");
free(exe_sections);
if(BLOCKMAX) {
*ctx->virname = "PE.NsPack.ExceededFileSize";
return CL_VIRUS;
} else {
return CL_CLEAN;
}
}
if ( !ssize || !dsize || dsize != exe_sections[0].vsz) break;
if (lseek(desc, start_of_stuff, SEEK_SET)==-1) break;
if (!(dest=cli_malloc(dsize))) break;
/* memset(dest, 0xfc, dsize); */
if (!(src=cli_malloc(ssize))) {
free(dest);
break;
}
/* memset(src, 0x00, ssize); */
cli_readn(desc, src, ssize);
eprva+=0x27a;
if (!(rep = cli_rawaddr(eprva, exe_sections, nsections, &err, fsize, hdr_size)) && err) break;
if (lseek(desc, rep, SEEK_SET)==-1) break;
if (cli_readn(desc, nbuff, 5)!=5) break;
eprva=eprva+5+cli_readint32(nbuff+1);
cli_dbgmsg("NsPack: OEP = %08x\n", eprva);
if(!(tempfile = cli_gentemp(NULL))) {
free(src);
free(dest);
free(exe_sections);
return CL_EMEM;
}
if((ndesc = open(tempfile, O_RDWR|O_CREAT|O_TRUNC|O_BINARY, S_IRWXU)) < 0) {
cli_dbgmsg("NsPack: Can't create file %s\n", tempfile);
free(tempfile);
free(src);
free(dest);
free(exe_sections);
return CL_EIO;
}
if (!unspack(src, dest, ctx, exe_sections[0].rva, EC32(optional_hdr32.ImageBase), eprva, ndesc)) {
free(src);
free(dest);
if (cli_leavetemps_flag)
cli_dbgmsg("NsPack: Unpacked and rebuilt executable saved in %s\n", tempfile);
else
cli_dbgmsg("NsPack: Unpacked and rebuilt executable\n");
fsync(ndesc);
lseek(ndesc, 0, SEEK_SET);
if(cli_magic_scandesc(ndesc, ctx) == CL_VIRUS) {
free(exe_sections);
close(ndesc);
if(!cli_leavetemps_flag) unlink(tempfile);
free(tempfile);
return CL_VIRUS;
}
} else {
free(src);
free(dest);
cli_dbgmsg("NsPack: Unpacking failed\n");
}
close(ndesc);
if(!cli_leavetemps_flag) unlink(tempfile);
free(tempfile);
break;
}
/* to be continued ... */
free(exe_sections);
return CL_CLEAN;
}
int cli_peheader(int desc, struct cli_exe_info *peinfo)
{
uint16_t e_magic; /* DOS signature ("MZ") */
uint32_t e_lfanew; /* address of new exe header */
/* Obsolete - see below
uint32_t min = 0, max = 0;
*/
struct pe_image_file_hdr file_hdr;
union {
struct pe_image_optional_hdr64 opt64;
struct pe_image_optional_hdr32 opt32;
} pe_opt;
struct pe_image_section_hdr *section_hdr;
struct stat sb;
int i;
unsigned int err, pe_plus = 0;
uint32_t valign, falign, hdr_size;
size_t fsize;
cli_dbgmsg("in cli_peheader\n");
if(fstat(desc, &sb) == -1) {
cli_dbgmsg("fstat failed\n");
return -1;
}
fsize = sb.st_size - peinfo->offset;
if(cli_readn(desc, &e_magic, sizeof(e_magic)) != sizeof(e_magic)) {
cli_dbgmsg("Can't read DOS signature\n");
return -1;
}
if(EC16(e_magic) != IMAGE_DOS_SIGNATURE && EC16(e_magic) != IMAGE_DOS_SIGNATURE_OLD) {
cli_dbgmsg("Invalid DOS signature\n");
return -1;
}
lseek(desc, 58, SEEK_CUR); /* skip to the end of the DOS header */
if(cli_readn(desc, &e_lfanew, sizeof(e_lfanew)) != sizeof(e_lfanew)) {
cli_dbgmsg("Can't read new header address\n");
/* truncated header? */
return -1;
}
e_lfanew = EC32(e_lfanew);
if(!e_lfanew) {
cli_dbgmsg("Not a PE file\n");
return -1;
}
if(lseek(desc, peinfo->offset + e_lfanew, SEEK_SET) < 0) {
/* probably not a PE file */
cli_dbgmsg("Can't lseek to e_lfanew\n");
return -1;
}
if(cli_readn(desc, &file_hdr, sizeof(struct pe_image_file_hdr)) != sizeof(struct pe_image_file_hdr)) {
/* bad information in e_lfanew - probably not a PE file */
cli_dbgmsg("Can't read file header\n");
return -1;
}
if(EC32(file_hdr.Magic) != IMAGE_NT_SIGNATURE) {
cli_dbgmsg("Invalid PE signature (probably NE file)\n");
return -1;
}
if ( (peinfo->nsections = EC16(file_hdr.NumberOfSections)) < 1 || peinfo->nsections > 96 ) return -1;
if (EC16(file_hdr.SizeOfOptionalHeader) < sizeof(struct pe_image_optional_hdr32)) {
cli_dbgmsg("SizeOfOptionalHeader too small\n");
return -1;
}
if(cli_readn(desc, &optional_hdr32, sizeof(struct pe_image_optional_hdr32)) != sizeof(struct pe_image_optional_hdr32)) {
cli_dbgmsg("Can't read optional file header\n");
return -1;
}
if(EC32(optional_hdr64.Magic)==PE32P_SIGNATURE) { /* PE+ */
if(EC16(file_hdr.SizeOfOptionalHeader)!=sizeof(struct pe_image_optional_hdr64)) {
cli_dbgmsg("Incorrect SizeOfOptionalHeader for PE32+\n");
return -1;
}
if(cli_readn(desc, &optional_hdr32 + 1, sizeof(struct pe_image_optional_hdr64) - sizeof(struct pe_image_optional_hdr32)) != sizeof(struct pe_image_optional_hdr64) - sizeof(struct pe_image_optional_hdr32)) {
cli_dbgmsg("Can't read optional file header\n");
return -1;
}
hdr_size = EC32(optional_hdr64.SizeOfHeaders);
pe_plus=1;
} else { /* PE */
if (EC16(file_hdr.SizeOfOptionalHeader)!=sizeof(struct pe_image_optional_hdr32)) {
/* Seek to the end of the long header */
lseek(desc, (EC16(file_hdr.SizeOfOptionalHeader)-sizeof(struct pe_image_optional_hdr32)), SEEK_CUR);
}
hdr_size = EC32(optional_hdr32.SizeOfHeaders);
}
valign = (pe_plus)?EC32(optional_hdr64.SectionAlignment):EC32(optional_hdr32.SectionAlignment);
falign = (pe_plus)?EC32(optional_hdr64.FileAlignment):EC32(optional_hdr32.FileAlignment);
hdr_size = PESALIGN(hdr_size, valign);
peinfo->section = (struct cli_exe_section *) cli_calloc(peinfo->nsections, sizeof(struct cli_exe_section));
if(!peinfo->section) {
cli_dbgmsg("Can't allocate memory for section headers\n");
return -1;
}
section_hdr = (struct pe_image_section_hdr *) cli_calloc(peinfo->nsections, sizeof(struct pe_image_section_hdr));
if(!section_hdr) {
cli_dbgmsg("Can't allocate memory for section headers\n");
free(peinfo->section);
peinfo->section = NULL;
return -1;
}
if(cli_readn(desc, section_hdr, peinfo->nsections * sizeof(struct pe_image_section_hdr)) != peinfo->nsections * sizeof(struct pe_image_section_hdr)) {
cli_dbgmsg("Can't read section header\n");
cli_dbgmsg("Possibly broken PE file\n");
free(section_hdr);
free(peinfo->section);
peinfo->section = NULL;
return -1;
}
for(i = 0; falign!=0x200 && i<peinfo->nsections; i++) {
/* file alignment fallback mode - blah */
if (falign && section_hdr[i].SizeOfRawData && EC32(section_hdr[i].PointerToRawData)%falign && !(EC32(section_hdr[i].PointerToRawData)%0x200)) {
falign = 0x200;
}
}
for(i = 0; i < peinfo->nsections; i++) {
peinfo->section[i].rva = PEALIGN(EC32(section_hdr[i].VirtualAddress), valign);
peinfo->section[i].vsz = PESALIGN(EC32(section_hdr[i].VirtualSize), valign);
peinfo->section[i].raw = PEALIGN(EC32(section_hdr[i].PointerToRawData), falign);
peinfo->section[i].rsz = PESALIGN(EC32(section_hdr[i].SizeOfRawData), falign);
if (!peinfo->section[i].vsz && peinfo->section[i].rsz)
peinfo->section[i].vsz=PESALIGN(EC32(section_hdr[i].SizeOfRawData), valign);
if (peinfo->section[i].rsz && !CLI_ISCONTAINED(0, (uint32_t) fsize, peinfo->section[i].raw, peinfo->section[i].rsz))
peinfo->section[i].rsz = (fsize - peinfo->section[i].raw)*(fsize>peinfo->section[i].raw);
}
if(pe_plus)
peinfo->ep = EC32(optional_hdr64.AddressOfEntryPoint);
else
peinfo->ep = EC32(optional_hdr32.AddressOfEntryPoint);
if(!(peinfo->ep = cli_rawaddr(peinfo->ep, peinfo->section, peinfo->nsections, &err, fsize, hdr_size)) && err) {
cli_dbgmsg("Broken PE file\n");
free(section_hdr);
free(peinfo->section);
peinfo->section = NULL;
return -1;
}
free(section_hdr);
return 0;
}